在其中心旋转UILabel

我想旋转一个UILabel在它的中心，但是当它旋转它改变它的位置。 它并不拘泥于其中心。 我正在使用下面的代码来旋转它：

 float fromAngle = atan2(m_locationBegan.y-lblText.center.y, m_locationBegan.x-lblText.center.x); //float toAngle = atan2(_location.y-lblText.center.y, _location.x-lblText.center.x); float toAngle = atan2(_location.y-lblText.center.y+5, _location.x-lblText.center.x+5); float newAngle = wrapd(m_currentAngle + (toAngle - fromAngle), 0, 2*3.14); CGAffineTransform cgaRotate = CGAffineTransformMakeRotation(newAngle); lblText.transform = cgaRotate; int oneInFifty = (newAngle*50)/(2*3.14); NSLog(@"%@",[NSString stringWithFormat:@"fromAngle: %f toAngle: %f Angle: %f 1in50: %i",fromAngle, toAngle, newAngle, oneInFifty]); 

有人可以帮助我阻止中心移动吗？

Answer 1

看看这个博客文章 。

例如：（ label = UILabel ）

 // UIView's transform property is a CGAffineTransform. [UIView beginAnimations:nil context:NULL]; // arguments are optional view.transform = CGAffineTransformMakeRotation(M_PI_2); [UIView commitAnimations]; // CALayer's transform property is a CATransform3D. // rotate around a vector (x, y, z) = (0, 0, 1) where positive Z points // out of the device's screen. label.layer.transform = CATransform3DMakeRotation(M_PI_2, 0, 0, 1);