在開發(fā)過程中,對(duì)于定時(shí)器相信大家都不陌生,在http://www.lxweimin.com/p/0194a0866872 這篇文章中,我有談過各種定時(shí)器的優(yōu)缺點(diǎn),這里就簡(jiǎn)單封裝一個(gè)實(shí)用的不依賴于RunLoop運(yùn)行模式的GCD定時(shí)器

• 首先GCD定時(shí)器本質(zhì)也是對(duì)象必須有一個(gè)強(qiáng)引用應(yīng)用著,不然就會(huì)被釋放,由于提供的是類方法,就定義一個(gè)全局靜態(tài)變量字典來保存timer對(duì)象

//存放timer對(duì)象
static NSMutableDictionary *timerDictionary;
//根據(jù)index來存儲(chǔ)不同的timer對(duì)象
static NSInteger timerIndex = 0;

- 提供了一下兩個(gè)類方法來初始化定時(shí)器,區(qū)別在于第一個(gè)初始化完成后自動(dòng)開啟定時(shí)器,第二個(gè)需要自己選擇開啟與否

//初始化定時(shí)器,默認(rèn)初始化完成后開啟

• (void)timerWithTimeInterval:(NSTimeInterval)timeInterval dispatchQueue:(dispatch_queue_t)dispatchQueue withBlock:(void(^)(XHR_dispatch_timer *))block;

//初始化定時(shí)器,需要手動(dòng)開啟

• (void)timerWithTimeInterval:(NSTimeInterval)timeInterval dispatchQueue:(dispatch_queue_t)dispatchQueue isOn:(BOOL)isOn withBlock:(void(^)(XHR_dispatch_timer *))block;

- 具體方法的實(shí)現(xiàn)如下
  

//初始化定時(shí)器

• (void)timerWithTimeInterval:(NSTimeInterval)timeInterval dispatchQueue:(dispatch_queue_t)dispatchQueue withBlock:(void (^)())block
  {
  //默認(rèn)方法自動(dòng)開啟定時(shí)器
  [self timerWithTimeInterval:timeInterval dispatchQueue:dispatchQueue isOn:YES withBlock:block];
  }

• (void)timerWithTimeInterval:(NSTimeInterval)timeInterval dispatchQueue:(dispatch_queue_t)dispatchQueue isOn:(BOOL)isOn withBlock:(void (^)(XHR_dispatch_timer *))block
  {
  XHR_dispatch_timer *timer = [[XHR_dispatch_timer alloc]initWithTimeInterval:timeInterval dispatchQueue:dispatchQueue withBlock:block];

  [self.timerDictionary setObject:timer forKey:[NSString stringWithFormat:@"timerIndex_%ld",timerIndex++]];
  //根據(jù)設(shè)置是否需要在初始化完成后開啟
  if (isOn) {
  timer.timerStatus = XHR_dispatch_timerStatusRuning;
  }
  }

- 那么解釋一下這里的XHR_dispatch_timer，它是定義在XHRTimer這個(gè)單例內(nèi)的一個(gè)私有類，是用來管理每一個(gè)timer對(duì)象的，以便在創(chuàng)建不同的timer對(duì)象執(zhí)行不同的任務(wù)，并且定義了一個(gè)定時(shí)器狀態(tài)枚舉來標(biāo)記運(yùn)作狀態(tài)，通過調(diào)整運(yùn)作狀態(tài)就可以控制定時(shí)器的開啟、暫停、取消等操作，也避免了多次開啟、暫停、取消而引起的bug,具體實(shí)現(xiàn)如下

• (instancetype)initWithTimeInterval:(NSTimeInterval)timeInterval dispatchQueue:(dispatch_queue_t)dispatchQueue withBlock:(void(^)(XHR_dispatch_timer *))block
  {
  if (self = [super init]) {
  //timer本質(zhì)也是對(duì)象必須有強(qiáng)應(yīng)用引用,不然就會(huì)被釋放
  self.timer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, dispatchQueue);
  //設(shè)置開始時(shí)間和時(shí)間間隔
  dispatch_source_set_timer(self.timer, DISPATCH_TIME_NOW, timeInterval * NSEC_PER_SEC, 0 * NSEC_PER_SEC);
  //設(shè)置回調(diào)時(shí)間
  dispatch_source_set_event_handler(self.timer, ^{
  block(self);
  });
  self.timerStatus = XHR_dispatch_timerStatusSuspend;
  }
  return self;
  }
• (void)setTimerStatus:(XHR_dispatch_timerStatus)timerStatus
  {
  if (!self.timer) return;
  if (timerStatus == XHR_dispatch_timerStatusSuspend && _timerStatus != XHR_dispatch_timerStatusSuspend) {
  dispatch_suspend(self.timer);
  }
  else if (timerStatus == XHR_dispatch_timerStatusRuning && _timerStatus == XHR_dispatch_timerStatusSuspend)
  {
  dispatch_resume(self.timer);
  }
  else if(timerStatus == XHR_dispatch_timerStatusCanceled && _timerStatus != XHR_dispatch_timerStatusCanceled)
  {
  dispatch_cancel(self.timer);
  self.timer = nil;
  }
  _timerStatus = timerStatus;
  }

- 暫停定時(shí)器的方法

//暫停定時(shí)器

• (void)suspend:(XHR_dispatch_timer *)timer
  {
  if (timer) {
  timer.timerStatus = XHR_dispatch_timerStatusSuspend;
  }
  }
• (void)suspendAllTimer
  {
  [self.timerDictionary enumerateKeysAndObjectsUsingBlock:^(id _Nonnull key, XHR_dispatch_timer *_Nonnull obj, BOOL * _Nonnull stop) {
  obj.timerStatus = XHR_dispatch_timerStatusSuspend;
  }];
  }

- 手動(dòng)開啟/繼續(xù) 定時(shí)器的方法

//手動(dòng)開啟/繼續(xù) 定時(shí)器

• (void)resume:(XHR_dispatch_timer *)timer
  {
  if (timer) {
  timer.timerStatus = XHR_dispatch_timerStatusRuning;
  }
  }
• (void)resumeAllTimer
  {
  [self.timerDictionary enumerateKeysAndObjectsUsingBlock:^(id _Nonnull key, XHR_dispatch_timer *_Nonnull obj, BOOL * _Nonnull stop) {
  obj.timerStatus = XHR_dispatch_timerStatusRuning;
  }];
  }

- 取消定時(shí)器

//取消定時(shí)器
//取消定時(shí)器

• (void)cancel:(XHR_dispatch_timer *)timer
  {
  if (timer) {
  timer.timerStatus = XHR_dispatch_timerStatusCanceled;
  }
  [self.timerDictionary enumerateKeysAndObjectsUsingBlock:^(id _Nonnull key, id _Nonnull obj, BOOL * _Nonnull stop) {
  if ([obj isEqual:timer]) {
  [self.timerDictionary removeObjectForKey:key];
  return;
  }
  }];
  }
• (void)cancelAllTimer
  {
  [self.timerDictionary enumerateKeysAndObjectsUsingBlock:^(id _Nonnull key, XHR_dispatch_timer *_Nonnull obj, BOOL * _Nonnull stop) {
  obj.timerStatus = XHR_dispatch_timerStatusCanceled;
  }];
  [self.timerDictionary removeAllObjects];
  }

注：
- 調(diào)用方法和NSTimer類似,使用類方法,需要執(zhí)行的代碼直接寫在方法的block中,非常方便.需要注意的是,如果取消了定時(shí)器,如果想重新開啟就需要重新初始化,不然就會(huì)崩潰。
- bolock傳出去的參數(shù)是為了供外部解決循環(huán)應(yīng)用問題的

作者:胥鴻儒
demo地址:https://github.com/xuhongru/GCDTimer