NSTimer 的初始化
初始化方法：有五種初始化方法
- (NSTimer *)timerWithTimeInterval:(NSTimeInterval)ti invocation:(NSInvocation *)invocation repeats:(BOOL)yesOrNo;
//例如:
//初始化一個Invocation對象
NSInvocation * invo = [NSInvocation invocationWithMethodSignature:[[self class] instanceMethodSignatureForSelector:@selector(init)]];
[invo setTarget:self];
[invo setSelector:@selector(timerAction)];
NSTimer * timer = [NSTimer timerWithTimeInterval:1 invocation:invo repeats:YES];
//加入主循環池中
[[NSRunLoop mainRunLoop]addTimer:timer forMode:NSDefaultRunLoopMode];
//開始循環
[timer fire];
- (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)ti invocation:(NSInvocation *)invocation repeats:(BOOL)yesOrNo;
//例如:
NSTimer * timer = [NSTimer scheduledTimerWithTimeInterval:1 invocation:invo repeats:YES];
- (NSTimer *)timerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;
//例如:
NSTimer * timer = [NSTimer timerWithTimeInterval:1 target:self selector:@selector(timerAction) userInfo:nil repeats:NO];
- (NSTimer *)scheduledTimerWithTimeInterval:(NSTimeInterval)ti target:(id)aTarget selector:(SEL)aSelector userInfo:(id)userInfo repeats:(BOOL)yesOrNo;
//例如:
NSTimer * timer = [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(timerAction:) userInfo:@"123" repeats:YES];
- (instancetype)initWithFireDate:(NSDate *)date interval:(NSTimeInterval)ti target:(id)t selector:(SEL)s userInfo:(id)ui repeats:(BOOL)repeats:(BOOL)yesOrNo;
//例如:
NSTimer * timer = [[NSTimer alloc]initWithFireDate:[NSDate distantPast] interval:1 target:self selector:@selector(timerAction:) userInfo:nil repeats:YES];
[[NSRunLoop mainRunLoop]addTimer:timer forMode:NSDefaultRunLoopMode];
它的屬性
@property (copy) NSDate *fireDate;//這是設置定時器的啟動時間，常用來管理定時器的啟動與停止
//啟動定時器
timer.fireDate = [NSDate distantPast];
//停止定時器
timer.fireDate = [NSDate distantFuture];
@property (readonly) NSTimeInterval timeInterval;//這個是一個只讀屬性，獲取定時器調用間隔時間
@property NSTimeInterval tolerance;//這是7.0之后新增的一個屬性，因為NSTimer并不完全精準，通過這個值設置誤差范圍
@property (readonly, getter=isValid) BOOL valid;//獲取定時器是否有效
@property (readonly, retain) id userInfo;//獲取參數信息
釋放,銷毀定時器
[timer invalidate];//是唯一的方法將定時器從循環池中移除
timer=nil;//同時置空
