iOS 在设置导航项时崩溃

Question

我有一个 UIButton，它在触地事件时弹出一个 UIViewController 来查看。在 viewDidLoad 中，应用程序崩溃并出现异常:

-[UILabel stringByTrimmingCharactersInSet:]: unrecognized selector sent to instance 0x16674e30

这是导致崩溃的代码:

viewController.navigationController.navigationBar.barStyle = UIBarStyleBlack;
UIImage *logo = [UIImage imageNamed:backgroundImageName];
UIImageView *logoView = [[UIImageView alloc] init];
logoView.image = logo;
logoView.frame = CGRectMake(0, 0, 50, 30);
viewController.navigationItem.titleView = logoView; // crash at this line

最后一行是导致崩溃的那一行。我将 SWRevealController 用作左滑抽屉式菜单。我有 5 个其他 UIViewControllers 使用完全相同的代码并正常工作，但我找不到它们与其他类之间的任何区别。我知道这可能看起来有点含糊，但我不确定现在该从哪里来解决这个问题。任何帮助将不胜感激。

这是主线程崩溃时的堆栈:

#0  0x378416a0 in objc_exception_throw ()
#1  0x2d4e47b6 in -[NSObject(NSObject) doesNotRecognizeSelector:] ()
#2  0x2d4e30ae in ___forwarding___ ()
#3  0x2d431dc8 in __forwarding_prep_0___ ()
#4  0x2fcfc78e in -[UINavigationItem initWithTitle:] ()
#5  0x2fcfc6dc in -[UIViewController(UINavigationControllerItem) navigationItem] ()
#6  0x00110b94 in -[CSUtility addleftButtonToNavItem:rightButton:background:rightButtonTitle:forViewController:revealViewController:overrideLeft:] at /Users/shawn/Documents/TruthIt/TruthIOS/TruthiOS/TruthiOS/CSUtility.m:59
#7  0x0012cd92 in -[CSQuestionDetailViewController viewDidLoad] at /Users/shawn/Documents/TruthIt/TruthIOS/TruthiOS/TruthiOS/CSQuestionDetailViewController.m:227
#8  0x2fc6995a in -[UIViewController loadViewIfRequired] ()
#9  0x2fc69718 in -[UIViewController view] ()
#10 0x2fdf5c2a in -[UINavigationController _startCustomTransition:] ()
#11 0x2fd13a16 in -[UINavigationController _startDeferredTransitionIfNeeded:] ()
#12 0x2fd13820 in -[UINavigationController __viewWillLayoutSubviews] ()
#13 0x2fd137b8 in -[UILayoutContainerView layoutSubviews] ()
#14 0x2fc65352 in -[UIView(CALayerDelegate) layoutSublayersOfLayer:] ()
#15 0x2f8eb942 in -[CALayer layoutSublayers] ()
#16 0x2f8e7166 in CA::Layer::layout_if_needed(CA::Transaction*) ()
#17 0x2f8e6ff8 in CA::Layer::layout_and_display_if_needed(CA::Transaction*) ()
#18 0x2f8e6a0c in CA::Context::commit_transaction(CA::Transaction*) ()
#19 0x2f8e681e in CA::Transaction::commit() ()
#20 0x2f8e054c in CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) ()
#21 0x2d4abf68 in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ ()
#22 0x2d4a98f6 in __CFRunLoopDoObservers ()
#23 0x2d4a9c42 in __CFRunLoopRun ()
#24 0x2d414470 in CFRunLoopRunSpecific ()
#25 0x2d414252 in CFRunLoopRunInMode ()
#26 0x321482ea in GSEventRunModal ()
#27 0x2fcc9844 in UIApplicationMain ()
#28 0x00111d7c in main at /Users/shawn/Documents/TruthIt/TruthIOS/TruthiOS/TruthiOS/main.m:16

这有点有趣，如果我将 View 代码切换到 viewWillAppear，我仍然会崩溃，而不是我的代码。这是堆栈跟踪:

Thread 1, Queue : com.apple.main-thread
#0  0x378416a0 in objc_exception_throw ()
#1  0x2d4e47b6 in -[NSObject(NSObject) doesNotRecognizeSelector:] ()
#2  0x2d4e30ae in ___forwarding___ ()
#3  0x2d431dc8 in __forwarding_prep_0___ ()
#4  0x2fcfc78e in -[UINavigationItem initWithTitle:] ()
#5  0x2fcfc6dc in -[UIViewController(UINavigationControllerItem) navigationItem] ()
#6  0x2fd1559a in -[UINavigationController _hasTranslucentNavigationBarIncludingViewController:] ()
#7  0x2fd1542c in -[UINavigationController _shouldNavigationBarInsetViewController:orOverlayContent:] ()
#8  0x2fd14c3e in -[UINavigationController _frameForViewController:] ()
#9  0x2fdf5c48 in -[UINavigationController _startCustomTransition:] ()
#10 0x2fd13a16 in -[UINavigationController _startDeferredTransitionIfNeeded:] ()
#11 0x2fd13820 in -[UINavigationController __viewWillLayoutSubviews] ()
#12 0x2fd137b8 in -[UILayoutContainerView layoutSubviews] ()
#13 0x2fc65352 in -[UIView(CALayerDelegate) layoutSublayersOfLayer:] ()
#14 0x2f8eb942 in -[CALayer layoutSublayers] ()
#15 0x2f8e7166 in CA::Layer::layout_if_needed(CA::Transaction*) ()
#16 0x2f8e6ff8 in CA::Layer::layout_and_display_if_needed(CA::Transaction*) ()
#17 0x2f8e6a0c in CA::Context::commit_transaction(CA::Transaction*) ()
#18 0x2f8e681e in CA::Transaction::commit() ()
#19 0x2f8e054c in CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) ()
#20 0x2d4abf68 in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ ()
#21 0x2d4a98f6 in __CFRunLoopDoObservers ()
#22 0x2d4a9c42 in __CFRunLoopRun ()
#23 0x2d414470 in CFRunLoopRunSpecific ()
#24 0x2d414252 in CFRunLoopRunInMode ()
#25 0x321482ea in GSEventRunModal ()
#26 0x2fcc9844 in UIApplicationMain ()
#27 0x00124cf4 in main at /Users/shawn/Documents/TruthIt/TruthIOS/TruthiOS/TruthiOS/main.m:16

好的，谢谢 rmaddy 的想法，我认为您正在做某事，但我仍然没有完全理解。我(愚蠢地知道，我在这里匆忙编码)有一个 UILabel 定义为名称标题。我将其更改为 questionTitle，现在我收到了一个不同的错误 - [UILabel copyWithZone] 无法识别的选择器发送到实例，这里再次是堆栈跟踪:

    Thread 1, Queue : com.apple.main-thread
#0  0x378416a0 in objc_exception_throw ()
#1  0x2d4e47b6 in -[NSObject(NSObject) doesNotRecognizeSelector:] ()
#2  0x2d4e30ae in ___forwarding___ ()
#3  0x2d431dc8 in __forwarding_prep_0___ ()
#4  0x2fcfb9a8 in -[UIViewController setTitle:] ()
#5  0x2de203b6 in -[NSObject(NSKeyValueCoding) setValue:forKey:] ()
#6  0x2de31ffc in -[NSObject(NSKeyValueCoding) setValue:forKeyPath:] ()
#7  0x2d4507e8 in -[NSArray makeObjectsPerformSelector:] ()
#8  0x2ffc44de in -[UINib instantiateWithOwner:options:] ()
#9  0x2ff260fa in -[UIViewController _loadViewFromNibNamed:bundle:] ()
#10 0x2fd87b58 in -[UIViewController loadView] ()
#11 0x2fc6979c in -[UIViewController loadViewIfRequired] ()
#12 0x2fc69718 in -[UIViewController view] ()
#13 0x2fdf5c2a in -[UINavigationController _startCustomTransition:] ()
#14 0x2fd13a16 in -[UINavigationController _startDeferredTransitionIfNeeded:] ()
#15 0x2fd13820 in -[UINavigationController __viewWillLayoutSubviews] ()
#16 0x2fd137b8 in -[UILayoutContainerView layoutSubviews] ()
#17 0x2fc65352 in -[UIView(CALayerDelegate) layoutSublayersOfLayer:] ()
#18 0x2f8eb942 in -[CALayer layoutSublayers] ()
#19 0x2f8e7166 in CA::Layer::layout_if_needed(CA::Transaction*) ()
#20 0x2f8e6ff8 in CA::Layer::layout_and_display_if_needed(CA::Transaction*) ()
#21 0x2f8e6a0c in CA::Context::commit_transaction(CA::Transaction*) ()
#22 0x2f8e681e in CA::Transaction::commit() ()
#23 0x2f8e054c in CA::Transaction::observer_callback(__CFRunLoopObserver*, unsigned long, void*) ()
#24 0x2d4abf68 in __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ ()
#25 0x2d4a98f6 in __CFRunLoopDoObservers ()
#26 0x2d4a9c42 in __CFRunLoopRun ()
#27 0x2d414470 in CFRunLoopRunSpecific ()
#28 0x2d414252 in CFRunLoopRunInMode ()
#29 0x321482ea in GSEventRunModal ()
#30 0x2fcc9844 in UIApplicationMain ()
#31 0x0008cccc in main at /Users/shawn/Documents/TruthIt/TruthIOS/TruthiOS/TruthiOS/main.m:16

Answer 1

从堆栈跟踪来看，您似乎正在尝试使用 initWithTitle: 创建一个新的导航项，但您将 UILabel 传递给初始化程序而不是 NSString。也许您想将标签的值传递给初始化程序？检查

[CSUtility addleftButtonToNavItem:rightButton:background:rightButtonTitle:forViewController:revealViewController:overrideLeft:] at /Users/shawn/Documents/TruthIt/TruthIOS/TruthiOS/TruthiOS/CSUtility.m:59