ViewWillAppear 没有被 UISplitViewController 调用

Question

背景与目标：我有一个基于 UISplitViewController 的 iPad 应用程序 - 到目前为止它支持 4 个方向，但现在我想将其锁定为仅横向。 我更改了左视图控制器的shouldAutorotateToInterfaceOrientation以仅支持横向模式，但这会阻止调用它的viewWillAppear。

详细信息：我的 iPad 的视图控制器组织如下：

window
`-- splitVC (UISplitViewController)
    `-- rootNav (UINavigationController)
        `-- hvc (HostManagerViewController, derived from UIViewController)
    `-- detailViewController (DetailViewController, derived from UIViewController)

这是在应用程序委托中实现的，如下所示：

- (BOOL)application:(UIApplication *)application
         didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    HostManagerViewController *hvc  = [[[HostManagerViewController alloc]
                                       initWithNibName:nil bundle:nil] autorelease];
    self.detailViewController = [[[DetailViewController alloc]
                                initWithNibName:nil bundle:nil] autorelease];
    UINavigationController *rootNav = [[[UINavigationController alloc]
                                        initWithRootViewController:hvc] autorelease];
    UISplitViewController *splitVC= [[[UISplitViewController alloc] init] autorelease];
    [splitVC setViewControllers:[NSArray arrayWithObjects:rootNav,
                                 detailViewController, nil]];

    splitVC.delegate = detailViewController;
    [window addSubview:splitVC.view];
    [window setRootViewController:splitVC];
    return YES;
}

当 DetailViewController.m 和 HostManagerViewController.m 都被调用时，viewWillAppear 被调用 包含

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return YES;
}
Console output:
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 3
Hostmanager: Viewdidload
Should rotate called to hostmanager with 1
Hostmanager: viewwillappear

但是当我将 HostManagerViewController 的代码更改为

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return (UIInterfaceOrientationIsLandscape(interfaceOrientation));
}

HostManagerViewController 的“viewWillAppear”时，不会调用该代码。控制台输出

Should rotate called to hostmanager with 1 (1 is the numeric value of interfaceOrientation)
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 3
Should rotate called to hostmanager with 3
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 3
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 3
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 1
Should rotate called to hostmanager with 3
Hostmanager: Viewdidload
Should rotate called to hostmanager with 1

Info.plist 中仅支持横向模式

编辑：插入 NSLog 消息以跟踪 shouldAutorotateToInterfaceOrientation、viewWillAppear 和 ViewDidLoad

Answer 1

我询问您使用的是哪个 iOS 版本，因为我尝试创建您的问题的简单重现，并发现 4.3 和 5.0 之间的行为有所不同。它实际上确实在 5.0 中进行了所有正确的调用。我相信这只是 UISplitviewController 的一个错误。 Splitview 控制器有很多问题。 aopsfan的回答并没有解决问题（我已经证实了这一点）。我建议对 uisplitviewcontroller 进行子类化，并重写 splitview 控制器的 viewwillappear、viewdidappear ，如下所示：

#import "testSplitViewController.h"

@implementation testSplitViewController

-(void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    NSString *reqSysVer = @"5.0";
    NSString *currSysVer = [[UIDevice currentDevice] systemVersion];
    if ([currSysVer compare:reqSysVer options:NSNumericSearch] == NSOrderedAscending)
        [[[self viewControllers] objectAtIndex:0] viewWillAppear:animated];
}

-(void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    NSString *reqSysVer = @"5.0";
    NSString *currSysVer = [[UIDevice currentDevice] systemVersion];
    if ([currSysVer compare:reqSysVer options:NSNumericSearch] == NSOrderedAscending)
        [[[self viewControllers] objectAtIndex:0] viewDidAppear:animated];
}
@end

您必须检查版本号，以免两次调用 viewDidAppear 。

或者如果可以的话，就使用 5.0 或更高版本，因为该错误似乎已修复。

Answer 2

基本上，由于 UISplitViewController 有两个部分，因此您需要一个 shouldAutorotate 的通用实现。我认为单独处理视图控制器的旋转可能会导致一些奇怪的副作用 - 但请注意，我无法复制您的 viewWillAppear 问题，所以这个解决方案实际上是一个猜测。

我建议创建一个非常简单的 UISplitViewController 子类。将其命名为“SplitViewController”，并在其 .m 文件中，删除除 shouldAutorotate 之外的所有内容，如下所示：

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return (UIInterfaceOrientationIsLandscape(interfaceOrientation));
}

现在更改 HostManagerViewController 和 DetailViewController 中的 shouldAutorotate 代码 返回：

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation {
    return YES;
}

现在，在您的应用程序委托中，使用此类而不是 UISplitViewController。这应该（可能）解决你的问题。

Answer 3

您将UISplitViewControler的委托设置为detailViewController

splitVC.delegate = detailViewController;

我认为阻止旋转的最佳位置将在DetailViewController中而不是在HostManagerViewController中。我将更改 HostManagerViewController 中的 -shouldAutorotateToInterfaceOrientation 以始终返回 YES，并在 DetailViewController 中添加：

-(BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (UIInterfaceOrientationIsLandscape == interfaceOrientation);
}