UIButton利用分类扩展方法（封装）

UIButton+BackgroundColor.h

#import <UIKit/UIKit.h>

@interface UIButton (BackgroundColor)

- (void)setBackgroundColor:(UIColor *)backgroundColor forState:(UIControlState)state;
@end

UIButton+BackgroundColor.m

#import "UIButton+BackgroundColor.h"

@implementation UIButton (BackgroundColor)

- (void)setBackgroundColor:(UIColor *)backgroundColor forState:(UIControlState)state
{
    [self setBackgroundImage:[UIButton imageWithColor:backgroundColor] forState:state];
}

+ (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;
}

@end