iOS 給View 設置指定位置圓角

`

• (instancetype)initWithFrame:(CGRect)frame
  {
  if (self = [super initWithFrame:frame]) {

    UIBezierPath *maskPath = [UIBezierPath bezierPathWithRoundedRect:self.bounds byRoundingCorners:UIRectCornerTopLeft | UIRectCornerTopRight cornerRadii:CGSizeMake(20, 20)];
    CAShapeLayer *maskLayer = [[CAShapeLayer alloc] init];
    maskLayer.frame = self.bounds;
    maskLayer.path = maskPath.CGPath;
    self.layer.mask = maskLayer;
    
    [self createUI];
  

  }
  return self;

}

`