根据状态设置UIButton的背景颜色

原理就是根据颜色返回一张尺寸1x1的图片然后设置为图片的背景色.

[oneBtn setBackgroundImage:[Utils createImageWithColor:[UIColor whiteColor]] forState:UIControlStateNormal];
[oneBtn setBackgroundImage:[Utils createImageWithColor:[UIColor blueColor]] forState:UIControlStateHighlighted];


#pragma mark - image new

+ (UIImage*)createImageWithColor:(UIColor*) color
{
    CGRect rect=CGRectMake(0,0, 1, 1);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
    UIImage *theImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return theImage;
}

//在某个类中实现
- (UIImage *)imageWithColor:(UIColor *)color
{
    CGRect rect = CGRectMake(0.0f, 0.0f, 1.0f, 1.0f);
    UIGraphicsBeginImageContext(rect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [color CGColor]);
    CGContextFillRect(context, rect);
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}