本期開發(fā)中, 遇到要修改特定UIViewController的UIStatusBar.
項(xiàng)目用的是:
[[UIApplication sharedApplication] setStatusBarStyle:UIStatusBarStyleLightContent];
這種方法已經(jīng)廢棄.
- (void)setStatusBarStyle:(UIStatusBarStyle)statusBarStyle animated:(BOOL)animated NS_DEPRECATED_IOS(2_0, 9_0, "Use -[UIViewController preferredStatusBarStyle]") __TVOS_PROHIBITED;
雖然還能用,但是在UIViewController生命周期哪個時間調(diào)用才是正確,而不會影響到其他UIViewController?
就在這時懶癌發(fā)作, 決定改成系統(tǒng)推薦的方式來管理UIStatusBar.
即UIViewController需要時,重寫以下方法:
- (UIStatusBarStyle)preferredStatusBarStyle NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED; // Defaults to UIStatusBarStyleDefault
- 第一步,修改info.plist文件
找到View controller-based status bar appearance選項(xiàng),如下圖:
將值改為YES,或者直接刪除改選項(xiàng)(默認(rèn)值就是YES).
- 第二步,實(shí)現(xiàn)'preferredStatusBarStyle'方法
- (UIStatusBarStyle)preferredStatusBarStyle{
return UIStatusBarStyleLightContent;
}
Run, 然并卵, 打個斷點(diǎn), 發(fā)現(xiàn)并沒有調(diào)用.
搜索發(fā)現(xiàn):
還是沒用.
后面事實(shí)證明, 完全多余. 如果你Xcode有相關(guān)代碼可以安心刪除.
諸如UINavigationController, UITabBarController 等系統(tǒng)UIViewController容器類, Apple會自己搞定,不用開發(fā)者操心.
// Override to return a child view controller or nil. If non-nil, that view controller's status bar appearance attributes will be used. If nil, self is used. Whenever the return values from these methods change, -setNeedsUpdatedStatusBarAttributes should be called.
#if UIKIT_DEFINE_AS_PROPERTIES
@property(nonatomic, readonly, nullable) UIViewController *childViewControllerForStatusBarStyle NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
@property(nonatomic, readonly, nullable) UIViewController *childViewControllerForStatusBarHidden NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
#else
- (nullable UIViewController *)childViewControllerForStatusBarStyle NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
- (nullable UIViewController *)childViewControllerForStatusBarHidden NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
#endif
但是這兩個API的確提醒了我, 應(yīng)該是Child ViewController的問題.
于是從RootViewController開始查找, 發(fā)現(xiàn) RootViewController 是一個UIViewController, 而UITabBarController是作為他的一個Child ViewController并完全蓋住它. 估計就是這里傳遞斷了.
于是新建一個RootViewController分類:
//這里RootViewController 是LMAppMainVC
//tabBarVC是UITabBarController
@implementation LMAppMainVC (LMStatusBarStyle)
- (UIViewController *)childViewControllerForStatusBarStyle{
return self.tabBarVC;
}
- (UIViewController *)childViewControllerForStatusBarHidden{
return self.tabBarVC;
}
@end
Run, 然后這次OK.棒棒噠.
簡單講講, 從App啟動開始UIStatusBar是怎么展示的.
- App啟動時的樣式,在下面這里設(shè)置:
- App啟動后,是一個傳遞鏈條.
首先RootViewController開始,如果RootViewController是系統(tǒng)容器類的ViewController, 如UINavigationController, UITabBarController 等會自動傳遞到當(dāng)前正在顯示的ViewController.
如果ViewController實(shí)現(xiàn)了以下方法:
- (nullable UIViewController *)childViewControllerForStatusBarStyle NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
- (nullable UIViewController *)childViewControllerForStatusBarHidden NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
會按照實(shí)現(xiàn)的方法來傳遞.
主要是,當(dāng)我們自己添加的Child ViewController, 就需要我們?nèi)?shí)現(xiàn)這兩個方法來往上傳遞.
當(dāng)Present一個ViewController的時候,系統(tǒng)也會自己往上傳遞,不需要我們操心.
當(dāng)然我們要注意non-full screen的情況,如下:
// This controls whether this view controller takes over control of the status bar's appearance when presented non-full screen on another view controller. Defaults to NO.
@property(nonatomic,assign) BOOL modalPresentationCapturesStatusBarAppearance NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
當(dāng)已經(jīng)無法再向上傳遞的時候, 系統(tǒng)會調(diào)用當(dāng)前ViewController的下面兩個方法,來展示UIStatusBar.
- (UIStatusBarStyle)preferredStatusBarStyle NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED; // Defaults to UIStatusBarStyleDefault
- (BOOL)prefersStatusBarHidden NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED; // Defaults to NO
// Override to return the type of animation that should be used for status bar changes for this view controller. This currently only affects changes to prefersStatusBarHidden.
- 手動靈活改變UIStatusBar
可以調(diào)用下面方法:
// This should be called whenever the return values for the view controller's status bar attributes have changed. If it is called from within an animation block, the changes will be animated along with the rest of the animation block.
- (void)setNeedsStatusBarAppearanceUpdate NS_AVAILABLE_IOS(7_0) __TVOS_PROHIBITED;
先設(shè)置好顯示不同樣式條件返回:
- (UIStatusBarStyle)preferredStatusBarStyle{
if (self.customNavigationBar.separateLine.hidden) {
return UIStatusBarStyleLightContent;
} else {
return UIStatusBarStyleDefault;
}
}
然后在需要的時候調(diào)用:
[self setNeedsStatusBarAppearanceUpdate];
重點(diǎn)東西就這么多.
解決問題期間搜索到錯誤的答案,也給提個醒. 具體那個錯誤答案,戳我
如下圖:
按照上面實(shí)現(xiàn)分類后, present 出來的UIViewController的UIStatusBar正常.
- (void)dismissViewControllerAnimated: (BOOL)flag completion: (void (^ __nullable)(void))completion NS_AVAILABLE_IOS(5_0);后就變不回來了.
@property(nullable, nonatomic,readonly,strong) UIViewController *visibleViewController; // Return modal view controller if it exists. Otherwise the top view controller.
原因是dismissViewControllerAnimated調(diào)用后立馬就引發(fā)系統(tǒng)刷新狀態(tài)欄, 但是這時被dismiss的ViewController沒有立馬消失, 所以visibleViewController依然是這個未消失的ViewController,導(dǎo)致系統(tǒng)調(diào)用了錯誤的preferredStatusBarStyle.
提示一點(diǎn)系統(tǒng)默認(rèn)是UIStatusBarStyleDefault, 如果App需要默認(rèn)的UIStatusBarStyleLightContent.
建個分類改改就OK:
@implementation UIViewController (LMStatusBarStyle)
- (UIStatusBarStyle)preferredStatusBarStyle {
return UIStatusBarStyleLightContent;
}
@end
OK, UIStatusBar的正確使用姿勢暫時就這么多.
2017.10.14 更新一個坑
self.navigationController.navigationBarHidden = NO
如果導(dǎo)航欄是隱藏的,然后再顯示,有可能導(dǎo)致顯示錯誤.
上面代碼會引發(fā)狀態(tài)欄的刷新,但是self.navigationController不會自動向viewControllers傳遞,而是自動調(diào)用- (UIStatusBarStyle)preferredStatusBarStyle方法.
所以需要我們手動實(shí)現(xiàn)傳遞方法:
- (UIViewController *)childViewControllerForStatusBarStyle;
- (UIViewController *)childViewControllerForStatusBarHidden;
建立UINavigationController分類
@implementation UINavigationController (StatusBar)
- (UIViewController *)childViewControllerForStatusBarStyle{
return self.viewControllers.lastObject;
}
- (UIViewController *)childViewControllerForStatusBarHidden{
return self.viewControllers.lastObject;
}
@end
2017.10.15 更新一個坑
self.navigationController.navigationBar.barStyle = UIBarStyleBlack;
設(shè)置barStyle為UIBarStyleBlack,會導(dǎo)致navigationController 的 preferredStatusBarStyle 默認(rèn)值 變?yōu)?UIStatusBarStyleLightContent
如果沒有設(shè)置任何UIStatusBarStyleLightContent, statusBar卻莫名其妙變?yōu)?code>UIStatusBarStyleLightContent, 那極有可能barStyle被設(shè)置為UIBarStyleBlack.
( 不知道是不是UITabBarController也具備相同特性的)
demo還是上面那個,可以打開下面注釋測試下:
//改變navigationController 的 preferredStatusBarStyle 默認(rèn)值 變?yōu)?UIStatusBarStyleLightContent
self.navigationController.navigationBar.barStyle = UIBarStyleBlack;
