ios - 将 UILabel 滑动到 View Controller 上

Question

我正在尝试以平滑的滑动类型动画从 UIViewController 顶部的起始位置移动 UILabel，以便它在 View 加载时从顶部向下滑动，然后在 y 位置停止大约 10 秒. 10 秒后，我想再次滑出 View 。

-(void) animateInstructionLabel
{
float newX = 50.0f;
float newY = 100.0f;

[UIView transitionWithView:self.lblInstruction
                  duration:10.0f
                   options:UIViewAnimationCurveEaseInOut
                animations:^(void) {
                    lblInstruction.center = CGPointMake(newX, newY);
                }
                completion:^(BOOL finished) {
                    // Do nothing
                }];
} 

但我不知道如何进行 10 秒延迟，然后在上面的方法内返回。最终结果是我希望它成为一个看起来像通知的标签，然后再次移出屏幕。

有人可以帮我把上面描述的这些部分放在一起吗？

编辑

我是根据下面的回答添加的:

-(void) animateInstructionLabel
{
float newX = lblInstruction.frame.origin.x;
float newY = 20.0f;

lblInstruction.center = CGPointMake(lblInstruction.frame.origin.x, -20.0f);
lblInstruction.bounds = CGRectMake(lblInstruction.frame.origin.x, -20.0f, 650.0f, 40.0f);

[UIView animateWithDuration:3.0f
                      delay:0
                    options:UIViewAnimationCurveEaseInOut
                 animations:^(void) {
                     lblInstruction.center = CGPointMake(newX, newY);
                 }
                 completion:^(BOOL finished) {
                     [UIView animateWithDuration:5.0f
                                           delay:5.0
                                         options:UIViewAnimationCurveEaseInOut
                                      animations:^(void) {
                                          lblInstruction.center = CGPointMake(newX, -20);
                                      }
                                      completion:^(BOOL finished) {
                                          // Do nothing
                                      }
                      ];
                 }
 ];
}

但是即使我在动画开始之前将 label.center 设置在屏幕外，我也看到它从 viewcontroller 的左上角移动到 viewcontroller 的中心。它没有保持在动画开始之前应该设置的 x 位置。

Answer 1

尝试在你的动画 block 之后添加这个(oldX，oldY 是旧坐标，在动画标签之前):

double delayInSeconds = 10.0;
dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(delayInSeconds * NSEC_PER_SEC));
dispatch_after(popTime, dispatch_get_main_queue(), ^(void){
    [UIView transitionWithView:self.lblInstruction
                      duration:10.0f
                       options:UIViewAnimationCurveEaseInOut
                    animations:^(void) {
                        lblInstruction.center = CGPointMake(oldX, oldY);
                    }
                    completion:^(BOOL finished) {
                        // Do nothing
                    }];
});