iOS Tabbar在iPhone X上布局错乱的问题

今天遇到了一个很奇怪的问题，项目采用的是TabbarController+NavigationBarController的模式进行构建，在NavgationBarController只有一个子控制器的时候，如果进行横屏跳转时再回来，会有一个闪动效果。经过一系列调试后，发现在NavgationBar跳转下一页面时，由于设置了hidesBottomBarWhenPushed属性，Tabbar的subviews会发生改变，如下

刚创建时：

image

跳转时：

image

可以看到，在跳转时tabbar的SubViews的数组地址和子View的地址都发生了改变。

在layoutSubViews中

在layoutSubViews方法中tabbarButton 的frame变了。
解决办法：

@interface DPTabbar : UITabBar

@property (nonatomic, strong) NSMutableArray * tabbars;

@property (nonatomic, strong) NSMutableArray * heightArray;

@end

static CGRect _theFrame;

@implementation DPTabbar

- (instancetype)initWithFrame:(CGRect)frame

{

    self = [super initWithFrame:frame];

    if (self) {

        _tabbars = [NSMutableArray array];

        _heightArray = [NSMutableArray array];

        self.frame = _theFrame;

    }

    return self;

}

- (void)layoutSubviews{

    [super layoutSubviews];

    [self statusReplay];

}

- (void)setFrame:(CGRect)frame{

    if (!CGRectEqualToRect(self.frame, _theFrame)) {

        frame = _theFrame;

    }

    [super setFrame:_theFrame];

}

- (void)statusMemory{

    NSArray *subViews = self.subviews;


    [_tabbars removeAllObjects];

    for (UIView * view in subViews) {

        if ([view isKindOfClass:NSClassFromString(@"UITabBarButton")]) {

            [_tabbars addObject:view];

        }

    }

}

- (void)heightMemory{

    [_heightArray removeAllObjects];

    for (UIView * view in _tabbars) {

        [_heightArray addObject:NSStringFromCGRect(view.frame)];

    }

}

- (void)statusReplay{

    NSMutableArray *array = [NSMutableArray array];

    NSArray *subViews = self.subviews;

    for (id view in subViews) {

        if ([view isKindOfClass:NSClassFromString(@"UITabBarButton")]) {

            [array addObject:view];

        }

    }

    NSInteger count = array.count;

    NSInteger heightCount = _heightArray.count;

    if (count != heightCount) return;

    for (NSInteger i = 0; i < count; i++) {

        UIView *view = [array objectAtIndex:i];

        view.frame = CGRectFromString(self.heightArray[i]);

    }

}

@end

然后在tabbarcontroller的ViewDidLoad中设置：

- (void)viewDidLoad{

    [super viewDidLoad];

    _dpTabbar = [DPTabbar new];

    [self setValue:_dpTabbar forKey:@"tabBar"];

    self.view.backgroundColor = [UIColor whiteColor];

    [self setVCs];

    [[NSNotificationCenter defaultCenter] addObserver:self

                                            selector:@selector(statusBarFrameDidChange)

                                                name:UIApplicationDidChangeStatusBarFrameNotification

                                              object:nil];

    [[NSNotificationCenter defaultCenter] addObserver:self

                                            selector:@selector(statusBarFramewillChange)

                                                name:UIApplicationWillChangeStatusBarFrameNotification

                                              object:nil];

}

- (void)statusBarFrameDidChange{

    [_dpTabbar statusReplay];

}

- (void)statusBarFramewillChange{

- (void)statusBarFramewillChange{

    if (_dpTabbar.tabbars.count == 0) {

        [_dpTabbar statusMemory];

    }

    if (_dpTabbar.tabbars.count > 0 && _dpTabbar.heightArray.count > 0){

        [_dpTabbar statusReplay];

        return;

    }

    [_dpTabbar heightMemory];

}

这样就可以解决。思路是在push前存储tabbar个Item的高度，并在状态栏改变之前即push到下一页面的时候，将tabbar新创的subViews中的tabbarButtonframe设为对应的tabbarButton的frame。