아이폰 앱 개발 팁(12) : Head First iPhone Development #3

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> Head First iPhone Development 정리 #3

Chapter 3. objective-c for the iPhone - Twitter needs variety

@property(in the .h file) & @synthesize(in the .m file) : tell Objective-C to autogenerate getter and setter methods.

-(The minus sign) : it's an instance method.

+(The plus sign) : it's an class method(at means it's static).

Property attributes and definitions

• readonly : When you don't want people modifying the property. You can still change the field value backing the property, but the compiler won't generate a setter.
• readwrite : When you want the property to be modifiable by people. The compiler will generate a getter and a setter for you. This is the default.
• copy : When you want to hold onto a copy of some value instead of the value itself; for example, if you want to hold onto an array and don't want people to be able to change its contents after they set it. This sends a copy message to the value passed in then retains that.
• retain : When you're dealing with object values. The compiler will retain the value you pass in and release the old value when a new one comes in.
• assign : When you're dealing with basic types, like ints, floats, etc. The compiler just creates a setter with a simple myField = value statement. This is the default, but not usually what you want.
• atomic : Locks, Generated accessors are multithread safe and use mutexes when changing a property value. (cf. nonatomic : unlocks)

Example

• retain : @ property (nonatomic, retain) NSString* myField;

- (NSString*) myField{
    return myField;
}
- (void)setMyField:(NSString *) newValue{
    if(newValue != myField){
        [myField release];
        myField = [newValue retain];
    }
}

• assign : @ property (nonatomic, assign) NSString* myField; (Unproper to the NSString!!!)

- (NSString*) myField{
    return myField;
}
- (void)setMyField:(NSString *) newValue{
    myField = newValue;
}

To keep your memory straight!!!

1. You must release objects you create with alloc, new, copy, or mutableCopy.
2. Consider everything else to have a retain count of 1 and in the autorelease pool.

TextField Done Editing

- (IBAction)textFieldDoneEditing: (id)sender

{

    [sender resignFirstResponder]; 

}

이미지 출처 : flickr.com