iPhone：重复转型
我试图表示一个在 iPhone 屏幕上旋转的视图。我有一个按钮，当你按下它时，视图会旋转 180 度。
我的问题是这仅在第一次有效。
代码如下：
-(IBAction) flip:(id)sender{
CGAffineTransform transform; //the transform matrix to be used below
//BEGIN ANIMATIONS
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:2.0];
//animate
if (flag){
transform = CGAffineTransformMakeRotation( RADIANS(180) );
} else {
transform = CGAffineTransformMakeRotation( RADIANS(-180) );
}
flag = !flag;
transform = CGAffineTransformTranslate(transform, 0, 0);
self.mySuview.transform = transform;
//COMMIT ANIMATIONS
[UIView commitAnimations];
}
第一次单击时，视图旋转正常，但是当您再次单击时，什么也没有发生。没有错误，视图没有变化。
我缺少什么？
谢谢 贡索
I'm trying to represent a view that rotates on the iphone screen. I have a button and when you press it, the view rotates 180 degrees.
My problem is that this only works the first time.
Here is the code:
-(IBAction) flip:(id)sender{
CGAffineTransform transform; //the transform matrix to be used below
//BEGIN ANIMATIONS
[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration:2.0];
//animate
if (flag){
transform = CGAffineTransformMakeRotation( RADIANS(180) );
} else {
transform = CGAffineTransformMakeRotation( RADIANS(-180) );
}
flag = !flag;
transform = CGAffineTransformTranslate(transform, 0, 0);
self.mySuview.transform = transform;
//COMMIT ANIMATIONS
[UIView commitAnimations];
}
The first time you click, the view spins alright, but when you click again NOTHING happens. No errors, no changes on the view.
What am I missing?
Thanks
Gonso
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评论（1）
您基本上将两次变换设置为相同。在 else {} 语句中，使用：
transform = CGAffineTransformMakeRotation( RADIANS(0) );
事实上，您的代码不是采用 180 并添加 -180，而是采用 180 并将其设置为 -180。
You are basically setting the transform to be the same both times. In your else {} statement, use:
transform = CGAffineTransformMakeRotation( RADIANS(0) );
As is, your code is not taking the 180 and adding -180, it's taking the 180 and setting it to -180.