OC
/**设置圆角*/
[view.layer setMasksToBounds:YES];
[view.layer setCornerRadius:6];
view.layer.maskedCorners = (CACornerMask)(UIRectCornerTopRight|UIRectCornerBottomLeft);

Swift
// 假设我的View的名称是myView
// 1. 定义圆角
myView.layer.cornerRadius = 10.0
// 2. 选择需要实现圆角的角
myView.layer.maskedCorners = [.layerMinXMaxYCorner, .layerMaxXMaxYCorner]
// 左上角 - .layerMinXMinYCorner
// 右上角 - .layerMaxXMinYCorner
// 左下角 - .layerMinXMaxYCorner
// 右下角 - .layerMaxXMaxYCorner