設定控制元件圓角，只設置上面兩個角的圓角，下面兩個角依然是直角，如圖效果：

程式碼（通過貝塞爾曲線重繪layer層）：

UIImageView *picImageView = [[UIImageView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
    picImageView.backgroundColor = [UIColor greenColor];
    [self.view addSubview:picImageView];
    
    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:picImageView.bounds byRoundingCorners:UIRectCornerTopLeft|UIRectCornerTopRight cornerRadii:CGSizeMake(10, 10)]; // UIRectCornerBottomRight通過這個設定
    
    CAShapeLayer *maskLayer = [CAShapeLayer layer];
    maskLayer.frame = picImageView.bounds;
    maskLayer.path = maskPath.CGPath;
    
    picImageView.layer.mask = maskLayer;