概述：UIRotationGestureRecognizer旋转手势，继承于UIGestureRecognizer类，相对于UIGestureRecognizer多了两个属性值。
/*获取旋转的弧度*/
@property (nonatomic) CGFloat rotation;
/*获取旋转的速度,单位为弧度/秒*/
@property (nonatomic,readonly) CGFloat velocity;
案例：图像的旋转
/*声明*/
@property CGFloat rotateScale;
@property CGFloat rotateRotation;
@property UIImage* rotateImage;
/*设置初始的缩放比例*/
rotateScale = 1.0;
rotateRotation = 0;
/*设置imageView允许用户交互，支持多点触碰*/
self.image_view.userInteractionEnabled = YES;
self.image_view.multipleTouchEnabled = YES;
rotateImage = [UIImage imageNamed:@"rotateImage.png"];
self.image_view.image = rotateImage;
UIRotationGestureRecognizer *rotationRecognizer = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotaGestureDetected:)];
[rotationRecognizer setDelegate:self];
/*加载到要旋转的图片*/
[self.image_view addGestureRecognizer:rotationRecognizer];
-(void) rotaGestureDetected:(UIRotationGestureRecognizer *)recognizer {
/*获取手势旋转的弧度*/
CGFloat rotation = recognizer.rotation;
/*根据当前缩放比计算图片缩放后的目标大小*/
CGSize targetSize = CGSizeMake(rotateImage.size.width * rotateScale,
rotateImage.size.height * rotateScale);
/*对图片进行缩放、旋转*/
self.image_view.image = [[rotateImage imageByScalingToSize:targetSize]
imageRotatedByRadians: rotateRotation + rotation];
/*如果旋转手势结束*/
if(recognizer.state == UIGestureRecognizerStateEnded)
{
rotateRotation = rotateRotation + rotation;
}
}
注：了解UIGestureRecognizer类请跳转https://www.jianshu.com/p/e206dc86f89a
