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[REMOVE] dots at the end of the comments
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Yannick
parent
01e3455d90
commit
d5c4e851da
@ -16,7 +16,7 @@ It is a general-purpose, object-oriented programming language that adds Smalltal
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// Single-line comments start with //
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/*
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Multi-line comments look like this.
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Multi-line comments look like this
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*/
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// Imports the Foundation headers with #import
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@ -30,7 +30,7 @@ Multi-line comments look like this.
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@import Foundation;
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// Your program's entry point is a function called
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// main with an integer return type.
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// main with an integer return type
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int main (int argc, const char * argv[])
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{
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// Create an autorelease pool to manage the memory into the program
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@ -60,7 +60,7 @@ int main (int argc, const char * argv[])
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// String
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NSString *worldString = @"World";
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NSLog(@"Hello %@!", worldString); // prints => "Hello World!"
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// NSMutableString is a mutable version of the NSString object.
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// NSMutableString is a mutable version of the NSString object
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NSMutableString *mutableString = [NSMutableString stringWithString:@"Hello"];
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[mutableString appendString:@" World!"];
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NSLog(@"%@", mutableString); // prints => "Hello World!"
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@ -114,7 +114,7 @@ int main (int argc, const char * argv[])
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[oneDecNum decimalNumberBySubtracting:twoDecNum];
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[oneDecNum decimalNumberByMultiplyingBy:twoDecNum];
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[oneDecNum decimalNumberByDividingBy:twoDecNum];
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NSLog(@"%@", oneDecNum); // prints => 10.99 as NSDecimalNumber is immutable.
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NSLog(@"%@", oneDecNum); // prints => 10.99 as NSDecimalNumber is immutable
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// BOOL literals
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NSNumber *yesNumber = @YES;
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@ -125,12 +125,12 @@ int main (int argc, const char * argv[])
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NSLog(@"%i", yesBool); // prints => 1
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// Array object
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// May contain different data types, but must be an Objective-C object.
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// May contain different data types, but must be an Objective-C object
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NSArray *anArray = @[@1, @2, @3, @4];
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NSNumber *thirdNumber = anArray[2];
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NSLog(@"Third number = %@", thirdNumber); // Print "Third number = 3"
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// NSMutableArray is mutable version of NSArray allowing to change items in array
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// and extend or shrink array object. Convenient, but not as efficient as NSArray.
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// and extend or shrink array object. Convenient, but not as efficient as NSArray
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NSMutableArray *mutableArray = [NSMutableArray arrayWithCapacity:2];
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[mutableArray addObject:@"Hello"];
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[mutableArray addObject:@"World"];
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@ -141,7 +141,7 @@ int main (int argc, const char * argv[])
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NSDictionary *aDictionary = @{ @"key1" : @"value1", @"key2" : @"value2" };
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NSObject *valueObject = aDictionary[@"A Key"];
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NSLog(@"Object = %@", valueObject); // Print "Object = (null)"
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// NSMutableDictionary also available as a mutable dictionary object.
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// NSMutableDictionary also available as a mutable dictionary object
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NSMutableDictionary *mutableDictionary = [NSMutableDictionary dictionaryWithCapacity:2];
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[mutableDictionary setObject:@"value1" forKey:@"key1"];
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[mutableDictionary setObject:@"value2" forKey:@"key2"];
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@ -150,7 +150,7 @@ int main (int argc, const char * argv[])
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// Set object
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NSSet *set = [NSSet setWithObjects:@"Hello", @"Hello", @"World", nil];
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NSLog(@"%@", set); // prints => {(Hello, World)} (may be in different order)
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// NSMutableSet also available as a mutable set object.
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// NSMutableSet also available as a mutable set object
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NSMutableSet *mutableSet = [NSMutableSet setWithCapacity:2];
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[mutableSet addObject:@"Hello"];
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[mutableSet addObject:@"Hello"];
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@ -209,7 +209,7 @@ int main (int argc, const char * argv[])
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int ii = 0;
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while (ii < 4)
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{
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NSLog(@"%d,", ii++); // ii++ increments ii in-place, after using its value.
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NSLog(@"%d,", ii++); // ii++ increments ii in-place, after using its value
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} // => prints "0,"
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// "1,"
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// "2,"
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@ -235,7 +235,7 @@ int main (int argc, const char * argv[])
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// "2,"
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// "3,"
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// Object for loop statement. Can be used with any Objective-C object type.
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// Object for loop statement. Can be used with any Objective-C object type
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for (id item in values) {
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NSLog(@"%@,", item);
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} // => prints "0,"
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@ -262,19 +262,19 @@ int main (int argc, const char * argv[])
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// Objects
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///////////////////////////////////////
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// Create an object instance by allocating memory and initializing it.
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// An object is not fully functional until both steps have been completed.
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// Create an object instance by allocating memory and initializing it
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// An object is not fully functional until both steps have been completed
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MyClass *myObject = [[MyClass alloc] init];
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// The Objective-C model of object-oriented programming is based on message
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// passing to object instances.
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// In Objective-C one does not simply call a method; one sends a message.
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// passing to object instances
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// In Objective-C one does not simply call a method; one sends a message
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[myObject instanceMethodWithParameter:@"Steve Jobs"];
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// Clean up the memory you used into your program
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[pool drain];
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// End of @autoreleasepool.
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// End of @autoreleasepool
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}
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// End the program
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@ -291,22 +291,22 @@ int main (int argc, const char * argv[])
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// {
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// type name; <= variable declarations;
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// }
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// @property type name; <= property declarations.
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// -/+ (type) Method declarations; <= Method declarations.
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// @property type name; <= property declarations
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// -/+ (type) Method declarations; <= Method declarations
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// @end
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@interface MyClass : NSObject <MyProtocol> // NSObject is Objective-C's base object class.
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{
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// Instance variable declarations (can exist in either interface or implementation file).
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// Instance variable declarations (can exist in either interface or implementation file)
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int count; // Protected access by default.
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@private id data; // Private access. (More convenient to declare in implementation file).
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@private id data; // Private access (More convenient to declare in implementation file)
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NSString *name;
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}
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// Convenient notation for public access variables to auto generate a setter method.
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// By default, setter method name is 'set' followed by @property variable name.
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// Convenient notation for public access variables to auto generate a setter method
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// By default, setter method name is 'set' followed by @property variable name
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@property int propInt; // Setter method name = 'setPropInt'
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@property (copy) id copyId; // (copy) => Copy the object during assignment.
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// (readonly) => Cannot set value outside @interface.
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@property (readonly) NSString *roString; // Use @synthesize in @implementation to create accessor.
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@property (copy) id copyId; // (copy) => Copy the object during assignment
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// (readonly) => Cannot set value outside @interface
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@property (readonly) NSString *roString; // Use @synthesize in @implementation to create accessor
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// You can customize the getter and setter names instead of using default 'set' name:
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@property (getter=lengthGet, setter=lengthSet:) int length;
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@ -323,14 +323,14 @@ int main (int argc, const char * argv[])
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// Constructor methods with arguments:
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- (id)initWithDistance:(int)defaultDistance;
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// Objective-C method names are very descriptive. Always name methods according to their arguments.
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// Objective-C method names are very descriptive. Always name methods according to their arguments
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@end // States the end of the interface.
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@end // States the end of the interface
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// To access public variables from the implementation file, @property generates a setter method
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// automatically. Method name is 'set' followed by @property variable name:
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MyClass *myClass = [[MyClass alloc] init]; // create MyClass object instance.
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MyClass *myClass = [[MyClass alloc] init]; // create MyClass object instance
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[myClass setCount:10];
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NSLog(@"%d", [myClass count]); // prints => 10
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// Or using the custom getter and setter method defined in @interface:
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@ -345,39 +345,39 @@ NSString *classMethodString = [MyClass classMethod];
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MyClass *classFromName = [MyClass myClassFromName:@"Hello"];
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// Call instance methods:
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MyClass *myClass = [[MyClass alloc] init]; // Create MyClass object instance.
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MyClass *myClass = [[MyClass alloc] init]; // Create MyClass object instance
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NSString *stringFromInstanceMethod = [myClass instanceMethodWithParameter:@"Hello"];
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// Selectors.
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// Selectors
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// Way to dynamically represent methods. Used to call methods of a class, pass methods
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// through functions to tell other classes they should call it, and to save methods
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// as a variable.
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// SEL is the data type. @selector() returns a selector from method name provided.
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// as a variable
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// SEL is the data type. @selector() returns a selector from method name provided
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// methodAParameterAsString:andAParameterAsNumber: is method name for method in MyClass
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SEL selectorVar = @selector(methodAParameterAsString:andAParameterAsNumber:);
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if ([myClass respondsToSelector:selectorVar]) { // Checks if class contains method.
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// Must put all method arguments into one object to send to performSelector function.
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if ([myClass respondsToSelector:selectorVar]) { // Checks if class contains method
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// Must put all method arguments into one object to send to performSelector function
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NSArray *arguments = [NSArray arrayWithObjects:@"Hello", @4, nil];
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[myClass performSelector:selectorVar withObject:arguments]; // Calls the method.
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[myClass performSelector:selectorVar withObject:arguments]; // Calls the method
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} else {
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// NSStringFromSelector() returns a NSString of the method name of a given selector.
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// NSStringFromSelector() returns a NSString of the method name of a given selector
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NSLog(@"MyClass does not have method: %@", NSStringFromSelector(selectedVar));
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}
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// Implement the methods in an implementation (MyClass.m) file:
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@implementation MyClass {
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long distance; // Private access instance variable.
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long distance; // Private access instance variable
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NSNumber height;
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}
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// To access a public variable from the interface file, use '_' followed by variable name:
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_count = 5; // References "int count" from MyClass interface.
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_count = 5; // References "int count" from MyClass interface
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// Access variables defined in implementation file:
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distance = 18; // References "long distance" from MyClass implementation.
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distance = 18; // References "long distance" from MyClass implementation
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// To use @property variable in implementation, use @synthesize to create accessor variable:
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@synthesize roString = _roString; // _roString available now in @implementation.
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@synthesize roString = _roString; // _roString available now in @implementation
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// Called before calling any class methods or instantiating any objects.
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// Called before calling any class methods or instantiating any objects
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+ (void)initialize
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{
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if (self == [MyClass class]) {
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@ -385,20 +385,20 @@ distance = 18; // References "long distance" from MyClass implementation.
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}
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}
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// Counterpart to initialize method. Called when an object's reference count is zero.
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// Counterpart to initialize method. Called when an object's reference count is zero
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- (void)dealloc
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{
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[height release]; // If not using ARC, make sure to release class variable objects
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[super dealloc]; // and call parent class dealloc.
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[super dealloc]; // and call parent class dealloc
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}
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// Constructors are a way of creating instances of a class.
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// Constructors are a way of creating instances of a class
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// This is a default constructor which is called when the object is initialized.
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- (id)init
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{
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if ((self = [super init])) // 'super' used to access methods from parent class.
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if ((self = [super init])) // 'super' used to access methods from parent class
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{
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self.count = 1; // 'self' used for object to call itself.
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self.count = 1; // 'self' used for object to call itself
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}
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return self;
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}
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@ -430,11 +430,11 @@ distance = 18; // References "long distance" from MyClass implementation.
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return @42;
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}
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// To create a private method, create the method in the @implementation but not in the @interface.
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// To create a private method, create the method in the @implementation but not in the @interface
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- (NSNumber *)secretPrivateMethod {
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return @72;
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}
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[self secretPrivateMethod]; // Calls private method.
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[self secretPrivateMethod]; // Calls private method
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// Methods declared into MyProtocol
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- (void)myProtocolMethod
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@ -442,7 +442,7 @@ distance = 18; // References "long distance" from MyClass implementation.
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// statements
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}
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@end // States the end of the implementation.
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@end // States the end of the implementation
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/*
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* A protocol declares methods that can be implemented by any class.
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@ -472,34 +472,34 @@ With all object interactions, follow the pattern of:
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(1) create the object, (2) use the object, (3) then free the object from memory.
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*/
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MyClass *classVar = [MyClass alloc]; // 'alloc' sets classVar's reference count to one. Returns pointer to object.
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[classVar release]; // Decrements classVar's reference count.
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// 'retain' claims ownership of existing object instance and increments reference count. Returns pointer to object.
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MyClass *newVar = [classVar retain]; // If classVar is released, object is still in memory because newVar is owner.
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[classVar autorelease]; // Removes ownership of object at end of @autoreleasepool block. Returns pointer to object.
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MyClass *classVar = [MyClass alloc]; // 'alloc' sets classVar's reference count to one. Returns pointer to object
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[classVar release]; // Decrements classVar's reference count
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// 'retain' claims ownership of existing object instance and increments reference count. Returns pointer to object
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MyClass *newVar = [classVar retain]; // If classVar is released, object is still in memory because newVar is owner
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[classVar autorelease]; // Removes ownership of object at end of @autoreleasepool block. Returns pointer to object
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// @property can use 'retain' and 'assign' as well for small convenient definitions.
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@property (retain) MyClass *instance; // Release old value and retain a new one (strong reference).
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@property (assign) NSSet *set; // Pointer to new value without retaining/releasing old (weak reference).
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// @property can use 'retain' and 'assign' as well for small convenient definitions
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@property (retain) MyClass *instance; // Release old value and retain a new one (strong reference)
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@property (assign) NSSet *set; // Pointer to new value without retaining/releasing old (weak reference)
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// Automatic Reference Counting (ARC)
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// Because memory management can be a pain, Xcode 4.2 and iOS 4 introduced Automatic Reference Counting (ARC).
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// ARC is a compiler feature that inserts retain, release, and autorelease automatically for you, so when using ARC,
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// you must not use retain, relase, or autorelease.
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// you must not use retain, relase, or autorelease
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MyClass *arcMyClass = [[MyClass alloc] init];
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// ... code using arcMyClass
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// Without ARC, you will need to call: [arcMyClass release] after you're done using arcMyClass. But with ARC,
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// there is no need. It will insert this release statement for you.
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// there is no need. It will insert this release statement for you
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// As for the 'assign' and 'retain' @property attributes, with ARC you use 'weak' and 'strong'.
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// As for the 'assign' and 'retain' @property attributes, with ARC you use 'weak' and 'strong'
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@property (weak) MyClass *weakVar; // 'weak' does not take ownership of object. If original instance's reference count
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// is set to zero, weakVar will automatically receive value of nil to avoid application crashing.
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@property (strong) MyClass *strongVar; // 'strong' takes ownership of object. Ensures object will stay in memory to use.
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// is set to zero, weakVar will automatically receive value of nil to avoid application crashing
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@property (strong) MyClass *strongVar; // 'strong' takes ownership of object. Ensures object will stay in memory to use
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// For regular variables (not @property declared variables), use the following:
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__strong NSString *strongString; // Default. Variable is retained in memory until it leaves it's scope.
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__weak NSSet *weakSet; // Weak reference to existing object. When existing object is released, weakSet is set to nil.
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__unsafe_unretained NSArray *unsafeArray; // Like __weak, but unsafeArray not set to nil when existing object is released.
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__strong NSString *strongString; // Default. Variable is retained in memory until it leaves it's scope
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__weak NSSet *weakSet; // Weak reference to existing object. When existing object is released, weakSet is set to nil
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__unsafe_unretained NSArray *unsafeArray; // Like __weak, but unsafeArray not set to nil when existing object is released
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```
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## Further Reading
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