diff options
| -rw-r--r-- | objective-c.html.markdown | 78 |
1 files changed, 69 insertions, 9 deletions
diff --git a/objective-c.html.markdown b/objective-c.html.markdown index a70351b5..f2787649 100644 --- a/objective-c.html.markdown +++ b/objective-c.html.markdown @@ -297,22 +297,28 @@ int main (int argc, const char * argv[]) } // Convenient notation for public access variables to auto generate a setter method. // By default, setter method name is 'set' followed by @property variable name. -@property int count; // Setter method name = 'setCount' -@property (copy) NSString *name; // (copy) => Copy the object during assignment. -@property (readonly) id data; // (readonly) => Cannot set value outside interface. +@property int propInt; // Setter method name = 'setPropInt' +@property (copy) id copyId; // (copy) => Copy the object during assignment. +// (readonly) => Cannot set value outside @interface. +@property (readonly) NSString *roString; // Use @synthesize in @implementation to create accessor. // You can customize the getter and setter names instead of using default 'set' name: @property (getter=lengthGet, setter=lengthSet:) int length; // Methods +/- (return type)methodSignature:(Parameter Type *)parameterName; -// + for class method +// + for class methods: + (NSString *)classMethod; ++ (MyClass *)myClassFromHeight:(NSNumber *)defaultHeight; -// - for instance method +// - for instance methods: - (NSString *)instanceMethodWithParameter:(NSString *)string; - (NSNumber *)methodAParameterAsString:(NSString*)string andAParameterAsNumber:(NSNumber *)number; +// Constructor methods with arguments: +- (id)initWithDistance:(int)defaultDistance; +// Objective-C method names are very descriptive. Always name methods according to their arguments. + @end // States the end of the interface. @@ -328,38 +334,86 @@ NSLog(@"%i", [myClass lengthGet]); // prints => 32 myClass.count = 45; NSLog(@"%i", myClass.count); // prints => 45 +// Call class methods: +NSString *classMethodString = [MyClass classMethod]; +MyClass *classFromName = [MyClass myClassFromName:@"Hello"]; + +// Call instance methods: +MyClass *myClass = [[MyClass alloc] init]; // Create MyClass object instance. +NSString *stringFromInstanceMethod = [myClass instanceMethodWithParameter:@"Hello"]; + +// Selectors. +// Way to dynamically represent methods. Used to call methods of a class, pass methods +// through functions to tell other classes they should call it, and to save methods +// as a variable. +// SEL is the data type. @selector() returns a selector from method name provided. +// methodAParameterAsString:andAParameterAsNumber: is method name for method in MyClass +SEL selectorVar = @selector(methodAParameterAsString:andAParameterAsNumber:); +if ([myClass respondsToSelector:selectorVar]) { // Checks if class contains method. + // Must put all method arguments into one object to send to performSelector function. + NSArray *arguments = [NSArray arrayWithObjects:@"Hello", @4, nil]; + [myClass performSelector:selectorVar withObject:arguments]; // Calls the method. +} else { + // NSStringFromSelector() returns a NSString of the method name of a given selector. + NSLog(@"MyClass does not have method: %@", NSStringFromSelector(selectedVar)); +} // Implement the methods in an implementation (MyClass.m) file: @implementation MyClass { long distance; // Private access instance variable. + NSNumber height; } // To access a public variable from the interface file, use '_' followed by variable name: _count = 5; // References "int count" from MyClass interface. // Access variables defined in implementation file: distance = 18; // References "long distance" from MyClass implementation. +// To use @property variable in implementation, use @synthesize to create accessor variable: +@synthesize roString = _roString; // _roString available now in @implementation. + +// Called before calling any class methods or instantiating any objects. ++ (void)initialize +{ + if (self == [MyClass class]) { + distance = 0; + } +} -// Call when the object is releasing +// Counterpart to initialize method. Called when an object's reference count is zero. - (void)dealloc { + [height release]; // If not using ARC, make sure to release class variable objects + [super dealloc]; // and call parent class dealloc. } -// Constructors are a way of creating classes +// Constructors are a way of creating instances of a class. // This is a default constructor which is called when the object is initialized. - (id)init { - if ((self = [super init])) + if ((self = [super init])) // 'super' used to access methods from parent class. { - self.count = 1; + self.count = 1; // 'self' used for object to call itself. } return self; } +// Can create constructors that contain arguments: +- (id)initWithDistance:(int)defaultDistance +{ + distance = defaultDistance; + return self; +} + (NSString *)classMethod { return [[self alloc] init]; } ++ (MyClass *)myClassFromHeight:(NSNumber *)defaultHeight +{ + height = defaultHeight; + return [[self alloc] init]; +} + - (NSString *)instanceMethodWithParameter:(NSString *)string { return @"New string"; @@ -370,6 +424,12 @@ distance = 18; // References "long distance" from MyClass implementation. return @42; } +// To create a private method, create the method in the @implementation but not in the @interface. +- (NSNumber *)secretPrivateMethod { + return @72; +} +[self secretPrivateMethod]; // Calls private method. + // Methods declared into MyProtocol - (void)myProtocolMethod { |