相关疑难解决方法(0)

我有一个应用程序,我有一个UIImageView显示主图像和另一个UIImageView被用作掩码,显示一个透明的圆形和不透明的外面,这个圆圈可以使用a移动UIPanGestureRecognizer,我想知道一个方法来裁剪里面的图像将圆圈变成新的图像.这是附加的代码和屏幕截图

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.

    // create pan gesture

    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self
                                                                          action:@selector(handlePan:)];
    [self.view addGestureRecognizer:pan];


    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    shapeLayer.path = [[self makeCircleAtLocation:self.view.center radius:100.0] CGPath];
    shapeLayer.strokeColor = [[UIColor clearColor] CGColor];
    shapeLayer.fillColor = nil;
    shapeLayer.lineWidth = 3.0;

    // Add CAShapeLayer to our view

    [self.view.layer addSublayer:shapeLayer];

    // Save this shape layer in a class property for future reference,
    // namely so we …