需求是需要上面圆弧效果
️PS：用贝塞尔曲线实现圆弧效果涉及到轻微的高中几何知识...
可以自行百度，其实只需要求出半径....
一、这是UIImage用贝塞尔曲线裁剪的效果：
image.png
代码实现
// 半径
CGFloat r = (SCREEN_WIDTH*0.5*SCREEN_WIDTH*0.5 + 80.0*80.0)/(2.0*80.0);
UIBezierPath *path = [UIBezierPath bezierPathWithRect:CGRectMake(0, 80.0, SCREEN_WIDTH, SCREEN_HEIGHT-80.0)];
[path addArcWithCenter:CGPointMake(SCREEN_WIDTH*0.5, r) radius:r startAngle:5/4.0*M_PI endAngle:8/4.0*M_PI clockwise:YES];
// 开启位图上下文
UIGraphicsBeginImageContextWithOptions(imageView.frame.size, NO, 0);
[path addClip];
// 绘制图片
[textImage drawInRect:imageView.frame];
// 获取当前图片
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
// 关闭上下文
UIGraphicsEndImageContext();
二、这是UIView用贝塞尔曲线裁剪的效果：
image.png
代码实现
// 半径
CGFloat r = (SCREEN_WIDTH*0.5*SCREEN_WIDTH*0.5 + 80.0*80.0)/(2.0*80.0);
UIBezierPath *path = [UIBezierPath bezierPathWithRect:CGRectMake(0, 80.0, SCREEN_WIDTH, SCREEN_HEIGHT-80.0)];
[path addArcWithCenter:CGPointMake(SCREEN_WIDTH*0.5, r) radius:r startAngle:5/4.0*M_PI endAngle:8/4.0*M_PI clockwise:YES];
// 开启位图上下文
UIGraphicsBeginImageContextWithOptions(imageView.frame.size, NO, 0);
[path addClip];
// 绘制图片
[textImage drawInRect:imageView.frame];
// 获取当前图片
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
// 关闭上下文
UIGraphicsEndImageContext();
imageView.image = image;
[self.view addSubview:imageView];
