iOS10及更早版本App崩溃：无法实例化_UIScrollViewLayoutGuide求排查方案

嘿，这个问题我之前帮同事排查过好几次，先给你拆解下核心原因：从日志里的Could not instantiate class named _UIScrollViewLayoutGuide能直接看出来，_UIScrollViewLayoutGuide是iOS 11才引入的私有系统类，你的旧设备系统版本肯定低于iOS 11，所以加载界面时才会触发崩溃。下面给你一步步的排查和解决思路：

一、先验证核心前提：确认旧设备的iOS版本 #

• 直接打开旧设备的「设置」→「通用」→「关于本机」，查看iOS版本号。如果是10.x及以下，那完全匹配这个错误的触发条件——低版本系统根本不认识这个类。

二、排查界面文件（XIB/Storyboard）的问题 #

从调用栈能看到崩溃是在加载HomeMainViewController的视图时触发的，重点检查这个界面里的UIScrollView相关设置：

• 打开对应的XIB/Storyboard，选中ScrollView，查看右侧「Size Inspector」里的「Content Layout Guide」和「Frame Layout Guide」是否被勾选启用。这两个是Xcode针对iOS11+提供的可视化约束工具，一旦启用，低版本系统解析XIB时就会找不到对应的_UIScrollViewLayoutGuide类，直接崩溃。

三、具体修复方案 #

方案1：修改XIB/Storyboard为兼容写法 #

• 取消ScrollView的「Content Layout Guide」和「Frame Layout Guide」勾选；
• 给ScrollView添加一个子视图（比如UIView，作为contentView）；
• 给contentView添加约束：top、leading、trailing、bottom都和ScrollView的边缘对齐，同时设置contentView的width等于ScrollView的width（横向滚动场景）或者height等于ScrollView的height（纵向滚动场景）；
• 之后所有需要放在ScrollView里的内容都加到这个contentView上，这样就能完美替代Layout Guide的作用，同时兼容iOS11以下系统。

方案2：调整项目的Deployment Target #

• 打开项目设置，找到「Deployment Info」里的「iOS Deployment Target」，把版本降到你需要兼容的最低版本（比如iOS9.0）；
• 注意：这一步只是确保项目编译时会考虑低版本系统的兼容性，但如果已经用了iOS11+的特性（比如Layout Guide），还是需要配合方案1修改界面。

方案3：代码动态适配（适合不想修改XIB的场景） #

在HomeMainViewController的viewDidLoad方法里，添加系统版本判断，动态替换约束：

- (void)viewDidLoad {
    [super viewDidLoad];
    
    if (@available(iOS 11.0, *)) {
        // iOS11及以上，保留原有Layout Guide约束
    } else {
        // 低版本系统，移除原有Layout Guide相关约束，手动添加兼容约束
        UIView *contentView = [[UIView alloc] init];
        contentView.translatesAutoresizingMaskIntoConstraints = NO;
        [self.scrollView addSubview:contentView];
        
        // 添加contentView和scrollView的约束
        [NSLayoutConstraint activateConstraints:@[
            contentView.topAnchor constraintEqualToAnchor:self.scrollView.topAnchor,
            contentView.leadingAnchor constraintEqualToAnchor:self.scrollView.leadingAnchor,
            contentView.trailingAnchor constraintEqualToAnchor:self.scrollView.trailingAnchor,
            contentView.bottomAnchor constraintEqualToAnchor:self.scrollView.bottomAnchor,
            contentView.widthAnchor constraintEqualToAnchor:self.scrollView.widthAnchor // 横向滚动用这个，纵向滚动换成heightAnchor
        ]];
        
        // 把原来放在Layout Guide上的子视图移到contentView上
        // ...
    }
}

四、额外验证步骤 #

• 修改完成后，用Xcode的「模拟器」选择低版本iOS（比如iOS10.3）运行，看看是否还会崩溃；
• 如果还是有问题，检查其他界面里的ScrollView是否也用了Layout Guide，因为可能不止这一个界面存在兼容问题。

附上你提供的错误日志，方便后续参考：

2019-12-30 16:52:04.784 Hospital[7075:164758] *** Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'Could not instantiate class named _UIScrollViewLayoutGuide' *** 
First throw call stack: 
( 0 CoreFoundation 0x000000010ad9fb0b __exceptionPreprocess + 171 
1 libobjc.A.dylib 0x000000010a804141 objc_exception_throw + 48 
2 CoreFoundation 0x000000010ae08625 +[NSException raise:format:] + 197 
3 UIKit 0x000000010c15368d UINibDecoderDecodeObjectForValue + 323 
4 UIKit 0x000000010c15353f -[UINibDecoder decodeObjectForKey:] + 89 
5 Foundation 0x0000000109b0e417 -[NSLayoutConstraint initWithCoder:] + 757 
6 UIKit 0x000000010c1537ff UINibDecoderDecodeObjectForValue + 693 
7 UIKit 0x000000010c15399d UINibDecoderDecodeObjectForValue + 1107 
8 UIKit 0x000000010c15353f -[UINibDecoder decodeObjectForKey:] + 89 
9 UIKit 0x000000010bbee9de -[UIView initWithCoder:] + 2209 
10 UIKit 0x000000010bc29687 -[UIScrollView initWithCoder:] + 71 
11 UIKit 0x000000010c1537ff UINibDecoderDecodeObjectForValue + 693 
12 UIKit 0x000000010c15399d UINibDecoderDecodeObjectForValue + 1107 
13 UIKit 0x000000010c15353f -[UINibDecoder decodeObjectForKey:] + 89 
14 UIKit 0x000000010bbee4ed -[UIView initWithCoder:] + 944 
15 UIKit 0x000000010c1537ff UINibDecoderDecodeObjectForValue + 693 
16 UIKit 0x000000010c15353f -[UINibDecoder decodeObjectForKey:] + 89 
17 UIKit 0x000000010bf62f70 -[UIRuntimeConnection initWithCoder:] + 178 
18 UIKit 0x000000010c1537ff UINibDecoderDecodeObjectForValue + 693 
19 UIKit 0x000000010c15399d UINibDecoderDecodeObjectForValue + 1107 
20 UIKit 0x000000010c15353f -[UINibDecoder a:] + 89 
21 UIKit 0x000000010bf6216d -[UINib instantiateWithOwner:options:] + 1262 
22 UIKit 0x000000010bcfcfc3 -[UIViewController _loadViewFromNibNamed:bundle:] + 381 
23 UIKit 0x000000010bcfd8d9 -[UIViewController loadView] + 177 
24 UIKit 0x000000010bcfdc0a -[UIViewController loadViewIfRequired] + 195 
25 UIKit 0x000000010bcfe45a -[UIViewController view] + 27 
26 Hospital 0x00000001086ecb00 $s15_Hospital15PagerScrollViewC03setcdE010toParentVC05pagesI0ySo16UIViewControllerC_SayAHGSgtF + 1152 
27 Hospital 0x00000001086f6b85 $s15_Hospital22HomeMainViewControllerC11viewDidLoadyyF + 3861 
28 Hospital 0x00000001086f6e9b $s15_Hospital22HomeMainViewControllerC11viewDidLoadyyFTo + 43 
29 UIKit 0x000000010bcfe01a -[UIViewController loadViewIfRequired] + 1235 
30 UIKit 0x000000010bd3ce6c -[UINavigationController _layoutViewController:] + 56 
31 UIKit 0x000000010bd3d74a -[UINavigationController _updateScrollViewFromViewController:toViewController:] + 466 
32 UIKit 0x000000010bd3d8bb -[UINavigationController _startTransition:fromViewController:toViewController:] + 127 
33 UIKit 0x000000010bd3ea03 -[UINavigationController _startDeferredTransitionIfNeeded:] + 843 
34 UIKit 0x000000010bd3fb41 -[UINavigationController __viewWillLayoutSubviews] + 58 
35 UIKit 0x000000010bf3160c -[UILayoutContainerView layoutSubviews] + 231 
36 UIKit 0x000000010bc1e55b -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 1268 
37 QuartzCore 0x000000010a572904 -[CALayer layoutSublayers] + 146 
38 QuartzCore 0x000000010a566526 _ZN2CA5Layer16layout_if_neededEPNS_11TransactionE + 370 
39 QuartzCore 0x000000010a5663a0 _ZN2CA5Layer28layout_and_display_if_neededEPNS_11TransactionE + 24 
40 QuartzCore 0x000000010a4f5e92 _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 294 
41 QuartzCore 0x000000010a522130 _ZN2CA11Transaction6commitEv + 468 
42 QuartzCore 0x000000010a522b37 _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 115 
43 CoreFoundation 0x000000010ad45717 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23 
44 CoreFoundation 0x000000010ad45687 __CFRunLoopDoObservers + 391 
45 CoreFoundation 0x000000010ad2a038 CFRunLoopRunSpecific + 440 
46 UIKit 0x000000010bb5508f -[UIApplication _run] + 468 
47 UIKit 0x000000010bb5b134 UIApplicationMain + 159 
48 Hospital 0x000000010872773b main + 75 
49 libdyld.dylib 0x000000010e5d965d start + 1 
) 
libc++abi.dylib: terminating with uncaught exception of type NSException

内容的提问来源于stack exchange，提问作者Jaseel.Dev