iOS 9兼容版本的NSTimer scheduledTimerWithTimeInterval：重複：block：？

Question

我在iOS 10中使用下面的代碼，但是當我在iOS 9中運行它時，它崩潰了。我不認爲NSTimer scheduledTimerWithTimeInterval:repeats:block:支持iOS 9.我如何實現一個可以在iOS 8-10中工作的計時器？

static NSTimer* timer = nil; 

- (void)documentInteractionControllerWillBeginPreview:(UIDocumentInteractionController *)controller 
{ 
    timer = [NSTimer scheduledTimerWithTimeInterval:0.1 repeats:YES block:^(NSTimer * _Nonnull timer) { 
     [[UIApplication sharedApplication] setStatusBarHidden:YES]; 
    }]; 
} 

-(void)documentInteractionControllerDidEndPreview:(UIDocumentInteractionController *)controller 
{ 
    [timer invalidate]; 
    [[UIApplication sharedApplication] setStatusBarHidden:YES]; 
} 

Answer 1

您似乎在使用iOS10中引入的功能。再往下，你鏈接的頁面是在iOS的2

https://developer.apple.com/documentation/foundation/nstimer/1408356-timerwithtimeinterval?language=objc

使用，而不是一個功能。

Answer 2

這個固定：

static NSTimer* timer = nil; 

- (void)documentInteractionControllerWillBeginPreview:(UIDocumentInteractionController *)controller 
{ 
    timer = [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(hideStatusBar) userInfo:nil repeats:YES]; 
} 

-(void)hideStatusBar 
{ 
    [[UIApplication sharedApplication] setStatusBarHidden:YES]; 
} 

-(void)documentInteractionControllerDidEndPreview:(UIDocumentInteractionController *)controller 
{ 
    [timer invalidate]; 
    [[UIApplication sharedApplication] setStatusBarHidden:YES]; 
}