android按钮下边框颜色渐变,UIButton，UIView添加渐变边框

思路参考

举例UIButtom思路：

1、 首先创建一个临时的 UIView

2、 然后利用 CAGradientLayer 在 UIView 上面进行渐变绘制

3、将UIView 进行截图返回 UIImage

4、将返回的 UIImage 设置到 UIButton 的 setBackgroundImage

这样就可以完成了一个UIButton 的渐变色 绘制，并且可以根据不用的颜色来设置Button UIControlStateNormal | UIControlStateHighlighted | UIControlStateDisabled 来进行设置效果。

5、在已经绘制好有渐变色的UIView 上面盖多一个白色的 UIView 比 上面那个UIView 小一些像素 即可

下面直接贴代码

/**

btnRect:按钮的frame

borderWidth:按钮的边框宽度

默认圆角为高度的1/2，修改圆角需要修改gradientLayer和whiteView的cornerRadius

*/

- (UIImage *)getImageWithFrame:(CGRect)btnRect withBorderWidth:(CGFloat)borderWidth{

CGFloat btnWidth = btnRect.size.width;

CGFloat btnHeight = btnRect.size.height;

//用来放置渐变色的view

UIView *crView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, btnWidth, btnHeight)];

CAGradientLayer *gradientLayer = [CAGradientLayer layer];

gradientLayer.colors = @[(__bridge id)[UIColor colorWithRed:1 green:172/255.0 blue:64/255.0 alpha:1].CGColor, (__bridge id)[UIColor colorWithRed:254/255.0 green:119/255.0 blue:119/255.0 alpha:1].CGColor];

gradientLayer.locations = @[@0.3, @0.7];

gradientLayer.startPoint = CGPointMake(0, 0);

gradientLayer.endPoint = CGPointMake(1.0, 0);

gradientLayer.frame = CGRectMake(0, 0, crView.frame.size.width, crView.frame.size.height);

gradientLayer.cornerRadius = btnHeight*1.0/2;

[crView.layer addSublayer:gradientLayer];

//空白view

UIView *whiteView = [[UIView alloc] initWithFrame:CGRectMake(borderWidth, borderWidth, btnWidth-borderWidth*2, btnHeight-borderWidth*2)];

whiteView.layer.cornerRadius = btnHeight*1.0/2;

whiteView.backgroundColor = [UIColor whiteColor];

[crView addSubview:whiteView];

//把配置好的view转变成image

CGSize s = CGSizeMake(btnWidth, btnHeight);

// 下面方法，第一个参数表示区域大小。第二个参数表示是否是非透明的。如果需要显示半透明效果，需要传NO，否则传YES。第三个参数就是屏幕密度了

UIGraphicsBeginImageContextWithOptions(s, NO, [UIScreen mainScreen].scale);

[crView.layer renderInContext:UIGraphicsGetCurrentContext()];

UIImage*image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

return image;

}

使用方法：

UIButton *btn = [UIButton buttonWithType:UIButtonTypeCustom];

btn.frame = CGRectMake(0, 200, 200, 50);

[btn setTitle:@"+关注" forState:UIControlStateNormal];

[btn setBackgroundImage:[self getImageWithFrame:btn.frame withBorderWidth:0.5] forState:UIControlStateNormal];

[self.view addSubview:btn];

参考文档还写了渐变文字的方法，我尝试了下没成功，改天再看