IOS設置其ID爲零後定時重啓iOS對象

Question

DemoViewController負責向用戶顯示教程。包含動畫和計時器以重複手勢演示，同時被用戶忽略。從DataViewController實例化。未被編輯，但後來重新啓動其內部計時器。我需要它完全消失，所以當用戶返回第一頁時不會再次創建它。

dataViewController.h

#import "DemoViewController.h" 
@property (strong,nonatomic) DemoViewController *demoController; 

dataViewController.h

-(void) viewWillAppear:(BOOL)animated { 
    // demoPageNumber is 0 
    if ((self.demoController== nil) && ([_pageNumber isEqualToNumber:demoPageNumber])){ 
     self.demoController = [[DemoViewController alloc] initWithView:self.view]; 
    } 
} 

-(void) viewWillDisappear:(BOOL)animated{ 
    [self.demoController free]; // invalidate timer, nil all internal objects 
    self.demoController=nil; // should free object 
} 

DemoViewController.m

-(void) free{ 
    [animationRespawnTimer invalidate]; 
    animationRespawnTimer=nil; 
} 

-(void) respawnDemoWithSelector:(SEL)selector{ 
    NSLog(@"Timer fired %@", self); 
    [self resetTimer]; 
    animationRespawnTimer = [NSTimer scheduledTimerWithTimeInterval:10 
                 target:self 
                 selector:selector 
                 userInfo:nil 
                 repeats:NO]; 
} 

-(void) showScrollDemo{ 


    NSLog(@"showScrollDemo fired"); 
    [self stopPreviousAnimations]; 
    scrollHandView.frame = CGRectMake(315.0, 700.0, 100, 100); 
    scrollHandView.hidden=NO; 
    scrollHandView.alpha=1; 

    [UIView animateWithDuration:3.0 
          delay: 0.0 
         options: (UIViewAnimationOptionCurveEaseOut | 
            UIViewAnimationOptionRepeat) 
        animations:^{ 

         [UIView setAnimationRepeatCount:3]; 
         scrollHandView.frame = CGRectMake(315.0, 300.0, 100, 100); 

        } 
        completion:^(BOOL finished){ 

         [UIView animateWithDuration:1.0 delay:0 
         options:UIViewAnimationOptionCurveEaseOut 
             animations:^{ 
              scrollHandView.alpha=0; 

          } 
          completion:^(BOOL finished){ 
          scrollHandView.hidden=YES; 

        [self respawnDemoWithSelector: @selector(showScrollDemo)]; 

          } 
         ]; 

       } 
]; 

}

當加載頁面時，如果是這樣的第一頁，demoController被實例化，並在清理完成後自定義免費方法，從頁面退出。根據我的理解，這應該刪除demoController對象及其所有內容，包括定時器。和調試區域恰恰相同！直到在新頁面上時，demoController計時器神祕地從以前的對象ID重新生成。

17:59:14.041 viewWillAppear begin (self.demoController null) 
18:00:05.346 viewWillAppear, <DemoViewController: 0x7580310> //demoController created 
18:00:15.786 in the demoController method the "showScrollDemo" is fired 
18:00:19.834 viewWillAppear end <DemoViewController: 0x7580310> 

頁面被加載，演示執行正常。現在我正在翻頁。 viewWillDisappear事件被觸發。

18:01:17.966 viewWillDisappear begin, send "free" message to demoController 
18:01:17.966 "free" was performed from <DemoViewController: 0x7580310> 
18:01:34.059 viewWillDisappear end (self.demoController null) 

因此，「self.demoController」爲空。然後demoController重新生成自己以前的ID

18:02:36.514 Timer fired <DemoViewController: 0x7580310> 

爲什麼？定時器不能重生，它被設置爲重複：NO。

Answer 1

我假設它是動畫的完成塊，它調用respawnDemoWithSelector並創建一個新的計時器。

根據這樣的回答：https://stackoverflow.com/a/9676508/1187415，你可以停止所有正在運行的 動畫與

[self.view.layer removeAllAnimations]; 

或者，你可以在布爾屬性done添加到這是在free方法設置 到YES的DemoViewController，和檢查動畫的完成塊：

if (!self.done) 
    [self respawnDemoWithSelector: @selector(showScrollDemo)]; 

UPDATE：動畫塊捕獲對self的強烈參考，從而防止 對象被解除分配。 「保留 - 循環」問題的標準解決方案 （假設您使用ARC）是對自我使用弱引用。這將是這樣的：

__weak typeof(self) weakSelf = self; 
[UIView animateWithDuration:3.0 
         delay: 0.0 
        options: (UIViewAnimationOptionCurveEaseOut | 
           UIViewAnimationOptionRepeat) 
       animations:^{ 

        [UIView setAnimationRepeatCount:3]; 
        weakSelf.scrollHandView.frame = CGRectMake(315.0, 300.0, 100, 100); 

       } 
       completion:^(BOOL finished){ 

        [UIView animateWithDuration:1.0 delay:0 
             options:UIViewAnimationOptionCurveEaseOut 
             animations:^{ 
              weakSelf.scrollHandView.alpha=0; 

             } 
             completion:^(BOOL finished){ 
              weakSelf.scrollHandView.hidden=YES; 
              [weakSelf respawnDemoWithSelector: @selector(showScrollDemo)]; 

             } 
         ]; 

       } 
]; 

weakSelf不不抱持着強烈的參考DemoViewController並設置爲nil 自動，如果它指向的對象，以被釋放。在這種情況下，塊內部發送到weakSelf的所有消息都不做任何事情。