手势识别器（UIGestureRecognizer）- UIRotationGestureRecognizer(旋转)

//
//  ViewController.m

#import "ViewController.h"

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];

// 给imageView添加手势
self.imageView.userInteractionEnabled = YES;

// 创建『旋转』手势
UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotation:)];

[self.imageView addGestureRecognizer:rotation];
}

- (void)rotation:(UIRotationGestureRecognizer *)recognizer
{
// 获取手势旋转的角度
NSLog(@"%f",recognizer.rotation);

//    self.imageView.transform = CGAffineTransformMakeRotation(recognizer.rotation);

// 默认传递的旋转的角度都是相对于最开始的位置
// 我们这里更改
self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, recognizer.rotation);
recognizer.rotation = 0; //清零
}

@end