diff options
Diffstat (limited to 'objective-c.html.markdown')
| -rw-r--r-- | objective-c.html.markdown | 44 |
1 files changed, 22 insertions, 22 deletions
diff --git a/objective-c.html.markdown b/objective-c.html.markdown index 248e132e..53f155a6 100644 --- a/objective-c.html.markdown +++ b/objective-c.html.markdown @@ -76,16 +76,16 @@ int main (int argc, const char * argv[]) short fortyTwoShort = [fortyTwoShortNumber shortValue]; // or 42 NSLog(@"%hi", fortyTwoShort); - NSNumber *fortyTwoShortNumber = [NSNumber numberWithShort:41]; - unsigned short fortyTwoUnsigned = [fortyTwoShortNumber unsignedShortValue]; // or 41 - NSLog(@"%hu", fortyTwoUnsigned); + NSNumber *fortyOneShortNumber = [NSNumber numberWithShort:41]; + unsigned short fortyOneUnsigned = [fortyOneShortNumber unsignedShortValue]; // or 41 + NSLog(@"%u", fortyOneUnsigned); NSNumber *fortyTwoLongNumber = @42L; long fortyTwoLong = [fortyTwoLongNumber longValue]; // or 42 NSLog(@"%li", fortyTwoLong); - NSNumber *fortyTwoLongNumber = @53L; - unsigned long fiftyThreeUnsigned = [fortyTwoLongNumber unsignedLongValue]; // or 53 + NSNumber *fiftyThreeLongNumber = @53L; + unsigned long fiftyThreeUnsigned = [fiftyThreeLongNumber unsignedLongValue]; // or 53 NSLog(@"%lu", fiftyThreeUnsigned); // Floating point literals @@ -118,6 +118,7 @@ int main (int argc, const char * argv[]) NSLog(@"%i", yesBool); // prints => 1 // Array object + // May contain different data types, but must be an Objective-C object. NSArray *anArray = @[@1, @2, @3, @4]; NSNumber *thirdNumber = anArray[2]; NSLog(@"Third number = %@", thirdNumber); // Print "Third number = 3" @@ -148,10 +149,6 @@ int main (int argc, const char * argv[]) [mutableSet addObject:@"Hello"]; NSLog(@"%@", mutableSet); // prints => {(Hello)} - // Set object - NSSet *set = [NSSet setWithObjects:@"Hello", @"Hello", @"World", nil]; - NSLog(@"%@", set); // prints => {(Hello, World)} - /////////////////////////////////////// // Operators /////////////////////////////////////// @@ -299,9 +296,9 @@ 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 name = 'setCount' +@property int count; // Setter method name = 'setCount' @property (copy) NSString *name; // (copy) => Copy the object during assignment. -@property (readonly) id data; // (readonly) => Declare only a getter method. +@property (readonly) id data; // (readonly) => Cannot set value outside interface. // You can customize the getter and setter names instead of using default 'set' name: @property (getter=lengthGet, setter=lengthSet:) int length; @@ -322,7 +319,7 @@ int main (int argc, const char * argv[]) // automatically. Method name is 'set' followed by @property variable name: MyClass *myClass = [[MyClass alloc] init]; // create MyClass object instance. [myClass setCount:10]; -NSLog(@"%@", [myClass count]); // prints => 10 +NSLog(@"%d", [myClass count]); // prints => 10 // Or using the custom getter and setter method defined in @interface: [myClass lengthSet:32]; NSLog(@"%i", [myClass lengthGet]); // prints => 32 @@ -349,7 +346,7 @@ NSLog(@"%li", distance); // prints => 18 } // Constructors are a way of creating classes -// This is a default constructor which is called when the object is creating +// This is a default constructor which is called when the object is initialized. - (id)init { if ((self = [super init])) @@ -410,31 +407,34 @@ With all object interactions, follow the pattern of: (1) create the object, (2) use the object, (3) then free the object from memory. */ -MyClass *classVar = [MyClass alloc]; // alloc sets classVar's reference count to one. Returns pointer to object. +MyClass *classVar = [MyClass alloc]; // 'alloc' sets classVar's reference count to one. Returns pointer to object. [classVar release]; // Decrements classVar's reference count. -// retain claims ownership of existing object instance and increments reference count. Returns pointer to object. +// 'retain' claims ownership of existing object instance and increments reference count. Returns pointer to object. MyClass *newVar = [classVar retain]; // If classVar is released, object is still in memory because newVar is owner. [classVar autorelease]; // Removes ownership of object at end of @autoreleasepool block. Returns pointer to object. -// @property can use retain or assign as well for small convenient definitions. +// @property can use 'retain' and 'assign' as well for small convenient definitions. @property (retain) MyClass *instance; // Release old value and retain a new one (strong reference). @property (assign) NSSet *set; // Pointer to new value without retaining/releasing old (weak reference). +// Automatic Reference Counting (ARC) // Because memory management can be a pain, Xcode 4.2 and iOS 4 introduced Automatic Reference Counting (ARC). // ARC is a compiler feature that inserts retain, release, and autorelease automatically for you, so when using ARC, // you must not use retain, relase, or autorelease. -MyClass *arcMyClass = [[MyClass alloc] init]; // Without ARC, you will need to call: [arcMyClass release] after -// you're done using arcMyClass. But with ARC, there is no need. It will insert this release statement for you. +MyClass *arcMyClass = [[MyClass alloc] init]; +// ... code using arcMyClass +// Without ARC, you will need to call: [arcMyClass release] after you're done using arcMyClass. But with ARC, +// there is no need. It will insert this release statement for you. -// As for the "assign" and "retain" @property attributes, with ARC you use "weak" and "strong". -@property (weak) MyClass *weakVar; // weak does not take ownership of object. If original instance's reference count +// As for the 'assign' and 'retain' @property attributes, with ARC you use 'weak' and 'strong'. +@property (weak) MyClass *weakVar; // 'weak' does not take ownership of object. If original instance's reference count // is set to zero, weakVar will automatically receive value of nil to avoid application crashing. -@property (strong) MyClass *strongVar; // strong takes ownership of object. Ensures object will stay in memory to use. +@property (strong) MyClass *strongVar; // 'strong' takes ownership of object. Ensures object will stay in memory to use. // For regular variables (not @property declared variables), use the following: __strong NSString *strongString; // Default. Variable is retained in memory until it leaves it's scope. __weak NSSet *weakSet; // Weak reference to existing object. When existing object is released, weakSet is set to nil. -__unsafe_unretained NSArray *unsafeArray; // Like __weak but unsafeArray not set to nil when existing object is released. +__unsafe_unretained NSArray *unsafeArray; // Like __weak, but unsafeArray not set to nil when existing object is released. ``` ## Further Reading |