ios-IOS-移除imageView

IOS-移除imageView

屏幕上有一張圖片需要在停留的時候全屏。

    UILongPressGestureRecognizer *hold = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(hold:)];
    hold.minimumPressDuration = 0;

    [self.photoImageView addGestureRecognizer:hold];

監聽器：

-(void)hold:(UILongPressGestureRecognizer *)sender{
    UIImageView *img = [[UIImageView alloc] initWithImage:self.photo];
    img.userInteractionEnabled = NO;

    if(sender.state == UIGestureRecognizerStateBegan){
        NSLog(@"state began");
        [self.view addSubview:img];
    } else if (sender.state == UIGestureRecognizerStateEnded){
        NSLog(@"state ended");
        [img removeFromSuperview];
    }
}

圖片成功添加到屏幕中，只有 [img removeFromSuperview]好像沒有響應。

結束狀態的NSlog也正常。

最佳回答：

-(void)hold:(UILongPressGestureRecognizer *)sender{
    //每次響應函數 img都是一個新alloc出來的UIImageView
    UIImageView *img = [[UIImageView alloc] initWithImage:self.photo];
    img.userInteractionEnabled = NO;

    if(sender.state == UIGestureRecognizerStateBegan){
        NSLog(@"state began");
        //添加新alloc出來的UIImageView，可以看到界面效果
        [self.view addSubview:img];
    } else if (sender.state == UIGestureRecognizerStateEnded){
        NSLog(@"state ended");
       //remove 新alloc出來的UIImageView當然沒有效果，它還沒有被add進去
        [img removeFromSuperview];
    }
}

改成這樣

-(void)hold:(UILongPressGestureRecognizer *)sender{
    if(sender.state == UIGestureRecognizerStateBegan){
        NSLog(@"state began");
        UIImageView *img = [[UIImageView alloc] initWithImage:self.photo];
        img.userInteractionEnabled = NO;
        img.tag = kTAG_PHOTO_IMAGE_VIEW
        [self.view addSubview:img];
    } else if (sender.state == UIGestureRecognizerStateEnded){
        NSLog(@"state ended");
        UIImageView *img = (UIImageView *)[self.view viewWithTag:kTAG_PHOTO_IMAGE_VIEW];
        [img removeFromSuperview];
    }
}