一 序言

• 中東國(guó)家的人們使用習(xí)慣和其他國(guó)家不太一致奄侠，我們一般是從左往右看钝吮，但是中東的人們習(xí)慣從右往左看。
• 隨著大屏手機(jī)的出現(xiàn)碘勉，側(cè)滑返回功能就顯得至關(guān)重要巷挥。但是正常情況下，當(dāng)進(jìn)入一個(gè)新的頁(yè)面時(shí)验靡，新頁(yè)面是從右往左慢慢顯示倍宾。當(dāng)返回上一個(gè)頁(yè)面時(shí)，右滑即可胜嗓。
• 但是中東國(guó)家恰恰相反高职，頁(yè)面時(shí)從左往右顯示，需要左滑返回上一個(gè)頁(yè)面辞州。

二 本文解決的問(wèn)題

• 如何正確處理系統(tǒng)語(yǔ)言和當(dāng)前APP語(yǔ)言問(wèn)題
• 如何做到中東鏡像
• 添加全面左滑手勢(shì)

三 準(zhǔn)備工作

• 本項(xiàng)目是通過(guò)第三方庫(kù)FDFullscreenPopGesture實(shí)現(xiàn)的怔锌，所以閱讀本文之前需要先熟悉該第三方庫(kù)的原理。傳輸?shù)刂? iOS-FDFullscreenPopGesture詳解

先看看效果圖

aribc.gif

四 開(kāi)始講解啦

4.1 如何正確處理系統(tǒng)語(yǔ)言和當(dāng)前APP語(yǔ)言關(guān)系

本項(xiàng)目寫了一個(gè)類RTLHelper，用于處理該問(wèn)題

#define AppLanguage @"AppLanguage"
#define ArabicLanguage @"ArabicLanguage"
#define EnglishLanguage @"EnglishLanguage"

// 判斷用戶當(dāng)前系統(tǒng)語(yǔ)言是否是阿語(yǔ)
+ (bool)isArabicSystemLanguage {
    if (!isArabicKay) {
        NSArray *languages = [NSLocale preferredLanguages];
        NSString *currentLanguage = [languages objectAtIndex:0];
        
        NSString *system_prefix_language = @"";
        if ([currentLanguage containsString:@"-"]) {
            NSArray *arr = [currentLanguage componentsSeparatedByString:@"-"];
            system_prefix_language = arr[0];
        } else {
            system_prefix_language = currentLanguage;
        }
        isArabicKay = [NSNumber numberWithBool:[system_prefix_language isEqualToString:@"ar"]];
    }
    return [isArabicKay boolValue];
}

// 判斷當(dāng)前APP是否是阿語(yǔ)
+ (bool)isRTL {
    NSString *language = [[NSUserDefaults standardUserDefaults] valueForKey:AppLanguage];
    if ([language isEqualToString:ArabicLanguage]) {
        return YES;
    }
    return NO;
}

4.2 如何做到中東鏡像翻轉(zhuǎn)

蘋果已經(jīng)幫我們做好了UI布局變動(dòng)的事項(xiàng)埃元，只要你的app是建立在約束環(huán)境中涝涤，并且實(shí)現(xiàn)了Leading以及Trailing兩個(gè)約束條件而不是Left和Right，那么岛杀，只要輸入幾句短短的代碼就可以輕松不費(fèi)力地完成整個(gè)UI布局的變動(dòng)阔拳。

/**
 設(shè)置視圖方向
 1.包括 push 和 pop 時(shí)的方向
 2.包括視圖布局的方向
 */
+ (void)initRTL {
    //APP阿拉伯語(yǔ)言
    bool isRTL = [RTLHelper isRTL];
    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"9.0") && isRTL) {
        [[UIView appearance] setSemanticContentAttribute:UISemanticContentAttributeForceRightToLeft];
    } else if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"9.0") && !isRTL) {
        [[UIView appearance] setSemanticContentAttribute:UISemanticContentAttributeForceLeftToRight];
    }
}

只要在AppDelegate中調(diào)用該方法或者切換APP語(yǔ)言后調(diào)用方法即可。

1.該方法會(huì)設(shè)置視圖的布局方向类嗤，比如從右往左布局糊肠，還是從左往右布局
2.設(shè)置push和pop時(shí)的方向。

4.3 切換APP語(yǔ)言后需要做什么事情

1.保存當(dāng)前APP語(yǔ)言為新設(shè)置的語(yǔ)言(保存一個(gè)key)
2.設(shè)置當(dāng)前APP的布局方向土浸，即semanticContentAttribute參數(shù)
3.移除棧中所有控制器罪针，并且給window設(shè)置一個(gè)新的rootVC，然后回到根控制器即可

相關(guān)代碼如下

• 保存當(dāng)前APP語(yǔ)言為新設(shè)置的語(yǔ)言(保存一個(gè)key)

[[NSUserDefaults standardUserDefaults] setValue:self.appLanguage forKey:AppLanguage];
[[NSUserDefaults standardUserDefaults] synchronize];

• 設(shè)置當(dāng)前APP的布局方向黄伊，即semanticContentAttribute參數(shù)

/**
 設(shè)置視圖方向
 1.包括 push 和 pop 時(shí)的方向
 2.包括視圖布局的方向
 */
+ (void)initRTL {
    //APP阿拉伯語(yǔ)言
    bool isRTL = [RTLHelper isRTL];
    if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"9.0") && isRTL) {
        [[UIView appearance] setSemanticContentAttribute:UISemanticContentAttributeForceRightToLeft];
    } else if (SYSTEM_VERSION_GREATER_THAN_OR_EQUAL_TO(@"9.0") && !isRTL) {
        [[UIView appearance] setSemanticContentAttribute:UISemanticContentAttributeForceLeftToRight];
    }
}

• 移除棧中所有控制器泪酱，并且給window設(shè)置一個(gè)新的rootVC，然后回到根控制器即可

// 新增TabBar后直接處理為重設(shè)APP界面
+ (void)setController {
    NSMutableArray *tbViewControllers = [NSMutableArray arrayWithArray:[[IContext getCtx].rootTabBarController viewControllers]];
    // 移除棧中所有控制器
    for (BaseNavigationController *navVc in tbViewControllers) {
        for (BaseViewController *vc in navVc.childViewControllers) {
            [vc removeFromParentViewController];
        }
    }
    [tbViewControllers removeAllObjects];
    [[IContext getCtx].rootTabBarController setViewControllers:tbViewControllers];

    // 給window設(shè)置一個(gè)新的根控制器
    MainViewController *tb = [[MainViewController alloc] init];
    [IContext getCtx].rootTabBarController = tb;
    [[IContext getCtx].rootWindow setRootViewController:tb];
    [[IContext getCtx].rootWindow makeKeyWindow];
}

[self.navigationController popToRootViewControllerAnimated:YES];

4.4 添加左滑手勢(shì)

1. 定義一個(gè)左滑的手勢(shì)的類

• RTLEdgePanGesture

@interface RTLEdgePanGesture : UIScreenEdgePanGestureRecognizer
@end

@implementation RTLEdgePanGesture

// 當(dāng)手勢(shì)側(cè)滑時(shí)會(huì)調(diào)用該方法,取到的是手指移動(dòng)后还最，在相對(duì)坐標(biāo)中的偏移量
// 注意:如果系統(tǒng)是阿語(yǔ),手勢(shì)已經(jīng)做了特殊處理,所以這個(gè)時(shí)候使用系統(tǒng)默認(rèn)的就好
- (CGPoint)translationInView:(UIView *)view {
    if ([RTLHelper isArabicSystemLanguage] && [RTLHelper isRTL]) {
        // APP 為阿語(yǔ)
        return [super translationInView:view];
    }
    if ([UIDevice currentDevice].systemVersion.doubleValue > 9.0) {
        CGPoint oldP = [super translationInView:view];
        // app為阿語(yǔ)  系統(tǒng)不是  反向處理
        return CGPointMake(-oldP.x, oldP.y);
    }
    return [super translationInView:view];
}
@end

1.如果系統(tǒng)是阿語(yǔ)言墓阀，并且APP也是阿語(yǔ)，則直接調(diào)用系統(tǒng)的方法即可拓轻，因?yàn)橄到y(tǒng)以及替我們做好了斯撮。這是一個(gè)大坑。
2.當(dāng)手勢(shì)在屏幕拖拽時(shí)扶叉，會(huì)調(diào)用該方法勿锅，從而返回當(dāng)前點(diǎn)擊區(qū)域的坐標(biāo)

添加一個(gè)左滑手勢(shì)的實(shí)例

• fd_rtlFullscreenPopGestureRecognizer

- (UIScreenEdgePanGestureRecognizer *)fd_rtlFullscreenPopGestureRecognizer {
    UIScreenEdgePanGestureRecognizer *rtlPanGestureRecognizer = objc_getAssociatedObject(self, _cmd);
    if (!rtlPanGestureRecognizer) {
        rtlPanGestureRecognizer = [[RTLEdgePanGesture alloc] init];
        rtlPanGestureRecognizer.edges = UIRectEdgeRight;
        if ([RTLHelper isArabicSystemLanguage] && ![RTLHelper isRTL]) {
            // APP 不是阿語(yǔ),強(qiáng)制把 APP 換成原來(lái)的
            rtlPanGestureRecognizer.edges = UIRectEdgeLeft;
        }
        objc_setAssociatedObject(self, _cmd, rtlPanGestureRecognizer, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    return rtlPanGestureRecognizer;
}

注意：如果系統(tǒng)是阿語(yǔ)，但是APP語(yǔ)言不是阿語(yǔ)枣氧，則需要把操作習(xí)慣變成正常的使用習(xí)慣

2. 新增左滑手勢(shì)的代理

• _FDFullRTLScreenPopGestureRecognizerDelegate

@interface _FDFullRTLScreenPopGestureRecognizerDelegate : NSObject <UIGestureRecognizerDelegate>

@property (nonatomic, weak) UINavigationController *navigationController;

@end

@implementation _FDFullRTLScreenPopGestureRecognizerDelegate

// 判斷當(dāng)前界面是否支持手勢(shì)滑動(dòng)返回
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer {
    // Ignore when no view controller is pushed into the navigation stack.
    if (self.navigationController.viewControllers.count <= 1) {
        return NO;
    }
    // Ignore when the active view controller doesn't allow interactive pop.
    UIViewController *topViewController = self.navigationController.viewControllers.lastObject;
    if (topViewController.fd_interactivePopDisabled) {
        return NO;
    }
    
    // Ignore when the beginning location is beyond max allowed initial distance to left edge.
    CGPoint beginningLocation = [gestureRecognizer locationInView:gestureRecognizer.view];
    CGFloat maxAllowedInitialDistance = topViewController.fd_interactivePopMaxAllowedInitialDistanceToLeftEdge;
    if (maxAllowedInitialDistance > 0 && beginningLocation.x > maxAllowedInitialDistance) {
        return NO;
    }
    
    // Ignore pan gesture when the navigation controller is currently in transition.
    if ([[self.navigationController valueForKey:@"_isTransitioning"] boolValue]) {
        return NO;
    }
    
    return YES;
}

• 定義左滑代理的實(shí)例

- (_FDFullRTLScreenPopGestureRecognizerDelegate *)fd_popRTLGestureRecognizerDelegate {
    _FDFullRTLScreenPopGestureRecognizerDelegate *rtlDelegate = objc_getAssociatedObject(self, _cmd);
    
    if (!rtlDelegate) {
        rtlDelegate = [[_FDFullRTLScreenPopGestureRecognizerDelegate alloc] init];
        rtlDelegate.navigationController = self;
        
        objc_setAssociatedObject(self, _cmd, rtlDelegate, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
    }
    return rtlDelegate;
}

3. 在fd_pushViewController:方法中替換系統(tǒng)自帶的手勢(shì)

- (void)fd_pushViewController:(UIViewController *)viewController animated:(BOOL)animated {
    // 自定義的手勢(shì)直接添加到interactivePopGestureRecognizer對(duì)應(yīng)的View上。
    // 實(shí)際上就是將系統(tǒng)的手勢(shì)事件轉(zhuǎn)發(fā)為自定義的手勢(shì)达吞，觸發(fā)的事件不變
    // doc:http://t.cn/RssK6mz 處理阿語(yǔ)翻轉(zhuǎn)手勢(shì)
    // 當(dāng)前APP語(yǔ)言為阿語(yǔ) || 系統(tǒng)語(yǔ)言為阿語(yǔ)
    if ([RTLHelper isArabicSystemLanguage] || [RTLHelper isRTL]) {
        if (![self.interactivePopGestureRecognizer.view.gestureRecognizers containsObject:self.fd_rtlFullscreenPopGestureRecognizer]) {
            // Add our own gesture recognizer to where the onboard screen edge pan gesture recognizer is attached to.
            [self.interactivePopGestureRecognizer.view addGestureRecognizer:self.fd_rtlFullscreenPopGestureRecognizer];
            
            // Forward the gesture events to the private handler of the onboard gesture recognizer.
            // interactivePopGestureRecognizer會(huì)操作一個(gè)指定的target , action “handleNavigationTransition”,
            // 通過(guò)Runtime動(dòng)態(tài)獲取到指定的target, 及action添加到自定義的手勢(shì)上酪劫。
            NSArray *internalTargets = [self.interactivePopGestureRecognizer valueForKey:@"targets"];
            // get releate target
            id internalTarget = [internalTargets.firstObject valueForKey:@"target"];
            // get handleNavigationTransition sel
            SEL internalAction = NSSelectorFromString(@"handleNavigationTransition:");
            self.fd_rtlFullscreenPopGestureRecognizer.delegate = self.fd_popRTLGestureRecognizerDelegate;
            // add target and action to this gesture
            [self.fd_rtlFullscreenPopGestureRecognizer addTarget:internalTarget action:internalAction];
            
            // Disable the onboard gesture recognizer.
            self.interactivePopGestureRecognizer.enabled = NO;
        }
    } else {
        // 添加一個(gè)正常的手勢(shì)即可
    }
}

只要系統(tǒng)語(yǔ)言為阿語(yǔ)或者APP語(yǔ)言是阿語(yǔ)刻剥，就添加阿語(yǔ)手勢(shì)

• 到此為止，工作完成滩字，我們就給中東鏡像添加了一個(gè)左滑手勢(shì)透敌，是不是很爽啊盯滚。

• 如有錯(cuò)誤，歡迎指正酗电，多多點(diǎn)贊魄藕，打賞更佳，您的支持是我寫作的動(dòng)力撵术。

項(xiàng)目連接地址 - FDFullScreenPopGestureDemo