<h1>我们要先知道</h1>
<h4>1.皮肤是什么？图片
2.换肤是什么？改变图片
3.通过什么方式改变？管理类加上通知的方法
4.改变那些图片？tabbar，navigation，我的，以及页面的背景。
5.换肤应用在那里？（1）节假日切换主题（2）切换夜晚模式（3）大主题
6.必要条件是什么？（1）不同主题的同一位置图片名称必须相同（2）我们的所有controller都继承于一个BaseViewController。BaseViewController里的方法</h4>（这里只以navigation和tarbar人为例了。）
<pre>

(void) reloadThemeImage {
ThemeManager * themeManager = [ThemeManager sharedThemeManager];

UIImage * navigationBackgroundImage = [themeManager themeImageWithName:@"navigationbar_background.png"];
[self.navigationController.navigationBar setBackgroundImage:navigationBackgroundImage forBarMetrics:UIBarMetricsDefault];

UIImage * tabBarBackgroundImage = [themeManager themeImageWithName:@"tabbar_background.png"];
[self.tabBarController.tabBar setBackgroundImage:tabBarBackgroundImage];
}
</pre>
在初始化BaseViewController的方法里加上通知
<pre>
(id) init {
if (self == [super init]) {
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(themeChangedNotfication:) name:@"通知名" object:nil];
}

[self reloadThemeImage];
return self;
}
//通知方法
(void) themeChangedNotfication:(NSNotification *)notification {
[self reloadThemeImage];
}
</pre>

点击换主题地方代码
<pre>

(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

ThemeManager * themeManager = [ThemeManager sharedThemeManager];
NSString * themeName = self.themeDataSource[indexPath.row];

if ([themeName isEqualToString:@"默认"]) {
themeName = nil;
}
// 记录当前主题名字
themeManager.themeName = themeName;
[[NSNotificationCenter defaultCenter] postNotificationName:kThemeChangedNotification object:nil];

// 主题持久化
NSUserDefaults * userDefaults = [NSUserDefaults standardUserDefaults];
[userDefaults setObject:themeName forKey:kThemeNameKey];
[userDefaults synchronize];

// 重新加载数据显示UITableViewCellAccessoryCheckmark 显示选中的对号 v
[self.tableView reloadData];

}
</pre>
<h2>管理类</h2>

.h文件
<pre>

import <Foundation/Foundation.h>

import <UIKit/UIKit.h>

@interface ThemeManager : NSObject

@property (nonatomic, copy) NSString * themeName; // 主题名字
@property (nonatomic, retain) NSDictionary * themePlistDict; // 主题属性列表字典

(ThemeManager *) sharedThemeManager;

(UIImage *) themeImageWithName:(NSString *)imageName;
@end
</pre>
.m文件
<pre>

import "ThemeManager.h"

import "NotificationMacro.h"

static ThemeManager * sharedThemeManager;
@implementation ThemeManager

(id) init {
if(self = [super init ]) {
NSString * themePath = [[NSBundle mainBundle] pathForResource:@"theme" ofType:@"plist"];
self.themePlistDict = [NSDictionary dictionaryWithContentsOfFile:themePath];
self.themeName = nil;
}
return self;
}

(ThemeManager *) sharedThemeManager {
@synchronized(self) {
if (nil == sharedThemeManager) {
sharedThemeManager = [[ThemeManager alloc] init];
}

return sharedThemeManager;
}

// Override 重写themeName的set方法

(void) setThemeName:(NSString *)themeName {
_themeName = themeName;
}
(UIImage *) themeImageWithName:(NSString *)imageName {
if (imageName == nil) {
return nil;
}

NSString * themePath = [self themePath];
NSString * themeImagePath = [themePath stringByAppendingPathComponent:imageName];
UIImage * themeImage = [UIImage imageWithContentsOfFile:themeImagePath];

return themeImage;
}

// 返回主题路径

(NSString *)themePath {
NSString * resourcePath = [[NSBundle mainBundle] resourcePath];
if (self.themeName == nil || [self.themeName isEqualToString:@""]) {
return resourcePath;
}
NSString * themeSubPath = [self.themePlistDict objectForKey:self.themeName]; // Skins/blue
NSString * themeFilePath = [resourcePath stringByAppendingPathComponent:themeSubPath]; // .../Skins/blue
return themeFilePath;
}
@end
</pre>
theme.plist是什么