iOS button边框

        UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];
        //同样来说btn也是有set方法的这里用的点语法
        btn.layer.masksToBounds=YES;
        btn.layer.cornerRadius=5;
        btn.layer.borderWidth=2;
        CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
        
        CGColorRef color = CGColorCreate(colorSpaceRef, (CGFloat[]){1,1,1,1});
        btn.layer.borderColor=color;

效果