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 
     
      #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] < 6)    {        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:2];    }    //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:1];    }    if ([cString length] != 6)    {        return [UIColor clearColor];    }        // Separate into r, g, b substrings    NSRange range;    range.location = 0;    range.length = 2;    //r    NSString *rString = [cString substringWithRange:range];    //g    range.location = 2;    NSString *gString = [cString substringWithRange:range];    //b    range.location = 4;    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(0, 0, 52, 44);        UIButton *rightButton = [UIButton buttonWithType:UIButtonTypeCustom];    rightButton.frame = CGRectMake(-6, 0, 52, 44);    rightButton.backgroundImageEdgeInsets = UIEdgeInsetsMake(7, 0, 7, 0);    //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:12.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，（1）宏定义RGB_COLOR和RGBA_COLOR可以设置颜色（2）UIColor+Hex扩展可以设置颜色（3）导航栏上面的BarButtonItem怎么设置为Button（4）Button一些常用和不常用的属性设置