說(shuō)到主題切換，那么久要做到切換主題瞬間，使所有相關(guān)的界面都發(fā)生變化，這就需要一種機(jī)制來(lái)將主題切換這是事件跑出來(lái)，并且接受主題切換事件的相關(guān)View 做出相應(yīng)的改變。想到這里你肯定也想到了NSNotification。沒(méi)錯(cuò)，這就是個(gè)不錯(cuò)的選擇，很適合我們的場(chǎng)景。下面具體來(lái)實(shí)現(xiàn)下。

不管是本地?fù)Q膚還是動(dòng)態(tài)換膚都需要一個(gè)Manager 進(jìn)行初始化主題模式，一半情況下都使用單例初始化就可以。

YNThemeManager.h

主要提供這幾個(gè)方法：

• (void)setupThemeNameArray:(NSArray *)array; 是用來(lái)初始化主題模式名稱的， 例如我們初始化兩個(gè)本地資源文件 YNTheme-White 和 YNTheme-Black 是bundle文件名稱

[[YNThemeManager sharedInstance] setupThemeNameArray:@[@"YNTheme-White", @"YNTheme-Black"]];

-- (BOOL)changeTheme:(NSString *)themeName; 用來(lái)改變主題模式的，在實(shí)際使用中只需要將已有的bundle名稱傳入即可

[[YNThemeManager sharedInstance] changeTheme:@"YNTheme-White"];

• + (UIColor *)colorWithID:(NSString *)colorID;用來(lái)獲取顏色
• + (UIImage *)imageWithName:(NSString *)imageName;用來(lái)獲取圖片

YNThemeManager.m

1.初始化

+ (instancetype)sharedInstance{
    
    static YNThemeManager *manager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        manager = [[YNThemeManager alloc] init];
    });
    return manager;
}

2.首先申明幾個(gè)屬性
bundle colorsMap themeArray

/** 主題bundle*/
@property (nonatomic,strong) NSBundle *bundle;
/** 顏色對(duì)照表*/
@property (nonatomic, copy) NSDictionary *colorsMap;
/** 主題數(shù)組*/
@property (nonatomic, copy) NSArray *themeArray;

3.主題數(shù)組賦值

- (void)setupThemeNameArray:(NSArray *)array{
    self.themeArray = array;
}

4.改變主題.m實(shí)現(xiàn)

- (BOOL)changeTheme:(NSString *)themeName{
    /** 判斷當(dāng)前切換主題是否在主題數(shù)組中*/
    if (![_themeArray containsObject:themeName]) {
        return NO;
    }
    /** 獲取bundle路徑*/
    NSBundle *bundle = [NSBundle bundleWithURL:[[NSBundle mainBundle] URLForResource:themeName withExtension:@"bundle"]];
    if (!bundle) {
        return NO;
    }
    /** 獲取bundle下plist文件路徑*/
    NSString *mapPath = [bundle pathForResource:@"ColorsMap" ofType:@"plist"];
    if (!mapPath) {
        return NO;
    }
    /** 獲取字典*/
    NSDictionary *colorsMap = [NSDictionary dictionaryWithContentsOfFile:mapPath];
      /** 賦值*/
    _themeName = themeName;
    self.bundle = bundle;
    self.colorsMap = colorsMap;
    /** 發(fā)送修改通知*/
    [self sendChangeThemeNotification];
    return YES;
}

/** 發(fā)送修改通知*/
- (void)sendChangeThemeNotification {
    [[NSNotificationCenter defaultCenter] postNotificationName:YNThemeChangeNotification object:nil];
}

5.獲取顏色

+ (UIColor *)colorWithID:(NSString *)colorID{
    if (!colorID) {
        return [UIColor clearColor];
    }
    return [UIColor yn_colorWithHexString:[[self class] colorStringWithID:colorID]];
}

/** 用來(lái)查找plist 文件中對(duì)應(yīng)色值的value */
+ (NSString *)colorStringWithID:(NSString *)colorID{
    
    NSArray *array = [colorID componentsSeparatedByString:@"_"];
    NSAssert(array.count > 1,  @"未找到對(duì)應(yīng)顏色-%@", colorID);
    NSDictionary *colorDict = [[YNThemeManager sharedInstance].colorsMap valueForKeyPath:array[0]];
    NSString *value = colorDict[colorID][@"Color"];
    NSAssert(value, @"未找到對(duì)應(yīng)顏色-%@", colorID);
    return value;
}

6.獲取圖片

+ (UIImage *)imageWithName:(NSString *)imageName {
    if (!imageName) {
        return nil;
    }
    NSBundle *bundle = [YNThemeManager sharedInstance].bundle;
    UIImage *image = [UIImage imageNamed:imageName inBundle:bundle compatibleWithTraitCollection:nil];
    NSAssert(image, @"未找到對(duì)應(yīng)圖片-%@", imageName);
    
    return image;
}

• 首先，控制器中的控件比較多，改變起來(lái)邏輯相當(dāng)復(fù)雜，邏輯可能不是很清楚
• 其次就是VC 中有些View 有很多層次，如；VC 中有一個(gè)HeaderView ，HeaderView中有BlackView，BlackView 中又有ImageView ,ImageView 中可能還有其他控件，如果要是在主題切換時(shí)改變ImageView,面臨的問(wèn)題就是
  VC ---->HeaderView -----> BlackView ---->ImageView
  這么長(zhǎng)的一個(gè)通知鏈。估計(jì)寫(xiě)起來(lái)會(huì)忍不住吐槽。同時(shí)維護(hù)起來(lái)也是很大的問(wèn)題。

基于以上問(wèn)題，我改變了設(shè)計(jì)思路，決定采用系統(tǒng)控件主動(dòng)接受通知。因此想到了對(duì)控件做手腳，以Label為例，為UILabel搞一個(gè)主題擴(kuò)展

• 大家可以看到其中有換膚屬性theme_textColor ，如下圖，我們?cè)趯傩詔heme_textColor 的Setter方法中有根據(jù)主題配置調(diào)用系統(tǒng)的相應(yīng)方法，然后對(duì)控件注冊(cè)監(jiān)聽(tīng)，等切換主題之后就會(huì)收到通知，然后執(zhí)行theme_didChanged方法，為控件設(shè)置正確的主題UI下面直接上代碼:

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@interface UILabel (YNTheme)

@property (nonatomic, copy) NSString *theme_textColor;

@property (nonatomic, copy) NSAttributedString *theme_attributedText;

@end

NS_ASSUME_NONNULL_END

@implementation UILabel (YNTheme)

- (void)theme_didChanged {
    [super theme_didChanged];
    if (self.theme_textColor) {
        self.textColor = [YNThemeManager colorWithID:self.theme_textColor];
    }
    if (self.attributedText) {
        self.attributedText = self.attributedText.theme_replaceRealityColor;
    }
}

// MARK:  ================ Setters ===========================
- (void)setTheme_textColor:(NSString *)color {
    self.textColor = [YNThemeManager colorWithID:color];
    objc_setAssociatedObject(self, @selector(theme_textColor), color, OBJC_ASSOCIATION_COPY_NONATOMIC);
    [self theme_registChangedNotification];
}

- (void)setTheme_attributedText:(NSAttributedString *)attributedText {
    self.attributedText = attributedText.theme_replaceRealityColor;
    [self theme_registChangedNotification];
}

- (void)setSDTextColorID:(NSString *)SDTextColorID {
    self.theme_textColor = SDTextColorID;
}

// MARK:  ================ Getters ===========================
- (NSString *)theme_textColor {
    return objc_getAssociatedObject(self, @selector(theme_textColor));
}

- (NSAttributedString *)theme_attributedText {
    return self.attributedText;
}

@end

• 當(dāng)然這里面會(huì)用到通知，我們專門創(chuàng)建一個(gè)NSObject+YNTheme分類，用于通知管理，廢話不多說(shuō)，直接上代碼。

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface NSObject (YNTheme)

/**
    注冊(cè)換膚監(jiān)聽(tīng)，不會(huì)重復(fù)監(jiān)聽(tīng)
    收到通知后會(huì)調(diào)用 theme_didChanged 方法
 */
- (void)theme_registChangedNotification;

/**
    注冊(cè)換膚監(jiān)聽(tīng)，不會(huì)重復(fù)監(jiān)聽(tīng)
    會(huì)立即調(diào)用一次 themeChangeBlock，和收到通知后調(diào)用
 */
- (void)theme_observerChangedUsingBlock:(void(^)(id observer))themeChangeBlock;

/** 子類重寫(xiě)，收到換膚通知會(huì)調(diào)用本方法*/
- (void)theme_didChanged;

@end

NS_ASSUME_NONNULL_END

#import "NSObject+YNTheme.h"
#import "YNThemeManager.h"
#import <objc/runtime.h>
#import "NSObject+YNDeallocExecutor.h"

static NSString *const kHasRegistChangedThemeNotification;

@interface NSObject ()

@property (nonatomic, copy) void(^theme_changeBlock)(id observer);

@end

@implementation NSObject (YNTheme)


- (void)theme_registChangedNotification {
    NSNumber *hasRegist = objc_getAssociatedObject(self, &kHasRegistChangedThemeNotification);
    /** 標(biāo)識(shí)是否已經(jīng)注冊(cè)通知，防止多次設(shè)置后導(dǎo)致同一個(gè)控件被注冊(cè)多次*/
    if (hasRegist) {
        return;
    }
    objc_setAssociatedObject(self, &kHasRegistChangedThemeNotification, @(YES), OBJC_ASSOCIATION_COPY_NONATOMIC);
    
    /** 接收通知*/
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(theme_didChanged) name:YNThemeChangeNotification object:nil];
    
    /** 暫時(shí)不明白*/
    __weak typeof(self) weakSelf = self;
    [self yn_executeAtDealloc:^{
        [[NSNotificationCenter defaultCenter] removeObserver:weakSelf];
    }];
}
- (void)theme_observerChangedUsingBlock:(void(^)(id observer))themeChangeBlock {
    self.theme_changeBlock = themeChangeBlock;
    [self theme_didChanged];
    [self theme_registChangedNotification];
}

- (void)theme_didChanged {
    if (self.theme_changeBlock) {
        __weak typeof(self) weakSelf = self;
        self.theme_changeBlock(weakSelf);
    }
}

- (void)setTheme_changeBlock:(void (^)(void))block {
    objc_setAssociatedObject(self, @selector(theme_changeBlock), block, OBJC_ASSOCIATION_COPY_NONATOMIC);
}

- (void (^)(void))theme_changeBlock {
    return objc_getAssociatedObject(self, @selector(theme_changeBlock));
}
@end

• 不知道大家發(fā)現(xiàn)沒(méi)有這里面涉及到一個(gè) block回調(diào)方法yn_executeAtDealloc這里面具體做什么，容我細(xì)細(xì)道來(lái)。
• 我們?cè)陂_(kāi)發(fā)過(guò)程經(jīng)常會(huì)遇到這樣的情況，我們想監(jiān)測(cè)一個(gè)NSObject對(duì)象到底有沒(méi)有釋放掉，通常的做法就是繼承于一個(gè)父類在其dealloc方法中進(jìn)行NSLog打印輸出了，這時(shí)候我們有沒(méi)有思考可以很方便的去實(shí)現(xiàn)dealloc方法的捕獲？下面和大家分享一個(gè)簡(jiǎn)單的方法，來(lái)實(shí)現(xiàn)這個(gè)過(guò)程，廢話不多說(shuō)直接上代碼。

#import <Foundation/Foundation.h>

NS_ASSUME_NONNULL_BEGIN

@interface NSObject (YNDeallocExecutor)

- (void)yn_executeAtDealloc:(void (^)(void))block;

@end

NS_ASSUME_NONNULL_END

#import "NSObject+YNDeallocExecutor.h"
#import <objc/runtime.h>

const void *YNDeallocExecutorsKey = &YNDeallocExecutorsKey;

@interface YNDeallocExecutor : NSObject

@property (nonatomic, copy) void(^deallocExecutorBlock)(void);

@end

@implementation YNDeallocExecutor

- (id)initWithBlock:(void(^)(void))deallocExecutorBlock {
    self = [super init];
    if (self) {
        _deallocExecutorBlock = [deallocExecutorBlock copy];
    }
    return self;
}

- (void)dealloc {
    _deallocExecutorBlock ? _deallocExecutorBlock() : nil;
}

@end

@implementation NSObject (YNDeallocExecutor)

- (void)yn_executeAtDealloc:(void (^)(void))block{
    if (block) {
        YNDeallocExecutor *executor = [[YNDeallocExecutor alloc] initWithBlock:block];
        /** 創(chuàng)建一個(gè)互斥鎖，保證在同一時(shí)間內(nèi)沒(méi)有其它線程對(duì)self對(duì)象進(jìn)行修改，起到線程的保護(hù)作用*/
        @synchronized (self) {
            [[self hs_deallocExecutors] addObject:executor];
        }
    }
}

- (NSHashTable *)hs_deallocExecutors {

    NSHashTable *table = objc_getAssociatedObject(self,YNDeallocExecutorsKey);
    if (!table) {
        table = [NSHashTable hashTableWithOptions:NSPointerFunctionsStrongMemory];
        objc_setAssociatedObject(self, YNDeallocExecutorsKey, table, OBJC_ASSOCIATION_RETAIN);
    }
    return table;
}

@end

以上就是我的換膚思路了，菜鳥(niǎo)小老弟，如有不足，請(qǐng)多多指教！！！