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(huán)池中
  [[NSRunLoop mainRunLoop]addTimer:timer forMode:NSDefaultRunLoopMode];
  //開始循環(huán)
  [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(shè)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(diào)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(zhǔn)，通過這個值設(shè)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(shù)信息

釋放,銷毀定時器

[timer invalidate];//是唯一的方法將定時器從循環(huán)池中移除

timer=nil;//同時置空