新建一个Category，命名为UIColor+Hex，表示UIColor支持十六进制Hex颜色设置。

UIColor+Hex.h文件，

#import <UIKit/UIKit.h>

#define RGBA_COLOR(R, G, B, A) [UIColor colorWithRed:((R) / 255.0f) green:((G) / 255.0f) blue:((B) / 255.0f) alpha:A]

#define RGB_COLOR(R, G, B) [UIColor colorWithRed:((R) / 255.0f) green:((G) / 255.0f) blue:((B) / 255.0f) alpha:1.0f]

@interface UIColor (Hex)

+ (UIColor *)colorWithHexString:(NSString *)color;

//从十六进制字符串获取颜色，

//color:支持@“#123456”、 @“0X123456”、 @“123456”三种格式

+ (UIColor *)colorWithHexString:(NSString *)color alpha:(CGFloat)alpha;

@end

上面的代码在开头是两个宏定义，就是对[UIColor colorWithRed:green:blue:alpha]方法的简化，在UIColor(Hex)中声明两个方法-colorWithHexString和-colorWithHexString:alpha，这个很好理解。

UIColor+Hex.m文件

#import "UIColor+Hex.h"

@implementation UIColor (Hex)

+ (UIColor *)colorWithHexString:(NSString *)color alpha:(CGFloat)alpha

{

    //删除字符串中的空格

    NSString *cString = [[color stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]] uppercaseString];

    // String should be 6 or 8 characters

    if ([cString length] < )

    {

        return [UIColor clearColor];

    }

    // strip 0X if it appears

    //如果是0x开头的，那么截取字符串，字符串从索引为2的位置开始，一直到末尾

    if ([cString hasPrefix:@"0X"])

    {

        cString = [cString substringFromIndex:];

    }

    //如果是#开头的，那么截取字符串，字符串从索引为1的位置开始，一直到末尾

    if ([cString hasPrefix:@"#"])

    {

        cString = [cString substringFromIndex:];

    }

    if ([cString length] != )

    {

        return [UIColor clearColor];

    }

    // Separate into r, g, b substrings

    NSRange range;

    range.location = ;

    range.length = ;

    //r

    NSString *rString = [cString substringWithRange:range];

    //g

    range.location = ;

    NSString *gString = [cString substringWithRange:range];

    //b

    range.location = ;

    NSString *bString = [cString substringWithRange:range];

    // Scan values

    unsigned int r, g, b;

    [[NSScanner scannerWithString:rString] scanHexInt:&r];

    [[NSScanner scannerWithString:gString] scanHexInt:&g];

    [[NSScanner scannerWithString:bString] scanHexInt:&b];

    return [UIColor colorWithRed:((float)r / 255.0f) green:((float)g / 255.0f) blue:((float)b / 255.0f) alpha:alpha];

}

//默认alpha值为1

+ (UIColor *)colorWithHexString:(NSString *)color

{

    return [self colorWithHexString:color alpha:1.0f];

}

@end

这样就扩展了UIColor，支持十六进制颜色设置。下面举个栗子，设置UIButton一些颜色特征，来说明该扩展的使用，

#import "UIColor+Hex.h"

//省略多余的代码

//设置导航栏右侧的BarButtonItem为Button

- (void)setupNavigationItem

{

    UIView *rightView = [[UIView alloc] init];

    rightView.bounds = CGRectMake(, , , );

    UIButton *rightButton = [UIButton buttonWithType:UIButtonTypeCustom];

    rightButton.frame = CGRectMake(-, , , );

    rightButton.backgroundImageEdgeInsets = UIEdgeInsetsMake(, , , );

    //kSetting是国际化的字符串"设置"

    [rightButton setTitle:NVSLocalizedString(@"kSetting", nil) forState:UIControlStateNormal];

    //使用宏定义的RGB_COLOR

//    [rightButton setTitleColor:RGB_COLOR(160, 170, 150) forState:UIControlStateHighlighted];

    //使用UIColor+Hex扩展

    [rightButton setTitleColor:[UIColor colorWithHexString:@"#708c3b"] forState:UIControlStateNormal];

    rightButton.titleLabel.font = [UIFont fontWithName:@"Heiti SC" size:.f];

    [rightButton setBackgroundImage:[UIImage imageNamed:@"device_setting_bg"]

                           forState:UIControlStateNormal];

    [rightButton setBackgroundImage:[UIImage imageNamed:@"device_setting_bg_press"]

                           forState:UIControlStateHighlighted];

    [rightButton addTarget:self action:@selector(settingBtnPresss:)

          forControlEvents:UIControlEventTouchUpInside];

    [rightView addSubview:rightButton];

    UIBarButtonItem *rightBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:rightView];

    [self.navigationItem setRightBarButtonItem:rightBarButtonItem animated:YES];

    [rightBarButtonItem release];

    [rightView release];

}

恩，使用差不多就这么简单，总结一下，本篇博客主要有以下几个细节或者说知识点，

（）宏定义RGB_COLOR和RGBA_COLOR可以设置颜色

（）UIColor+Hex扩展可以设置颜色

（）导航栏上面的BarButtonItem怎么设置为Button

（）Button一些常用和不常用的属性设置