@interface Car : NSObject

@property BOOL running;

@end

编译器翻译成


- (BOOL)running {
	return _reunning;
}

- (void)setRunning:(BOOL)newValue {
	_running = newValue;
}
 setter和getter方法

getter= 跟 setter=	 
改变默认getter、setter方法名
@property (getter=isRunning) BOOL running;

Car *honda = [[Car alloc] init];
honda.running = YES; // [honda setRunning: YES]
NSLog(@"%d", honda.running); // [honda isRunning]
NSLog(@"%d", [honda running]); // Error: method no longer exists

readonly 只读

nonatomic

property默认是线程安全，属性是原子性的

strong

强引用，循环引用会无法释放对象

weak

弱引用，父对象销毁，子对象指向父对象的指针置为0