Question

我试图在UIView上调用backgroundColor属性。

在我调酒之前，我会做以下事情：

@implementation UIView (Cat1)
+(void)load {
NSArray *selectors = @[
                     //Highliter swizzling
                     NSStringFromSelector(@selector(setBackgroundColor:)),
                     NSStringFromSelector(@selector(backgroundColor))
                     ];

[[self appearance] setBackgroundColor:[UIColor redColor]];

for (NSString *name in selectors) {
    SEL originalSelector = NSSelectorFromString(name);
    SEL swizzledSelector = NSSelectorFromString([NSString stringWithFormat:@"swizzled_%@",name]);
    Method originalMethod = class_getInstanceMethod(self, originalSelector);
    Method swizzledMethod = class_getInstanceMethod(self, swizzledSelector);
    class_addMethod(self,
                    originalSelector,
                    class_getMethodImplementation(self, originalSelector),
                    method_getTypeEncoding(originalMethod));
    class_addMethod(self,
                    swizzledSelector,
                    class_getMethodImplementation(self, swizzledSelector),
                    method_getTypeEncoding(swizzledMethod));
    method_exchangeImplementations(originalMethod, swizzledMethod);
}

然后，当调用swizzled方法时，除了调用原始方法之外我什么都不做：

-(void)swizzled_setBackgroundColor:(UIColor *)color {

[self iio_swizzled_setBackgroundColor:color];
}

然后，发生以下崩溃：2017-03-08 19:04:37.863 Develop-InsertViewer[69285:7916872] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Please file a radar on UIKit if you see this assertion.' *** First throw call stack: ( 0 CoreFoundation 0x0000000108506e65 __exceptionPreprocess + 165 1 libobjc.A.dylib 0x0000000107c7ddeb objc_exception_throw + 48 2 CoreFoundation 0x0000000108506cca +[NSException raise:format:arguments:] + 106 3 Foundation 0x00000001078ca5a2 -[NSAssertionHandler handleFailureInFunction:file:lineNumber:description:] + 169 4 UIKit 0x0000000106227b35 PushNextClassForSettingIMP + 469 5 UIKit 0x000000010622810a TaggingAppearanceObjectSetterIMP + 37 6 InsertFramework 0x00000001071332be -[UIView(Cat1) swizzled_setBackgroundColor:] + 62 7 UIKit 0x0000000105d78fca -[UILabel _commonInit] + 238 8 UIKit 0x0000000105d7913d -[UILabel initWithFrame:] + 94 9 UIKit 0x0000000105b9cc4e -[UIView init] + 62 10 0x0000000105533300 _TTOFCSo7UILabelcfT_S_ + 16 11 0x0000000105532e44 _TFCSo7UILabelCfT_S_ + 68 12 0x0000000105569be3 _TFC12InsertViewer21StarterViewControllercfT5coderCSo7NSCoder_GSqS0__ + 51 13 0x0000000105569d2d _TToFC12InsertViewer21StarterViewControllercfT5coderCSo7NSCoder_GSqS0__ + 45 14 UIKit 0x0000000105ecb7db -[UIClassSwapper initWithCoder:] + 241 15 UIKit 0x000000010609f822 UINibDecoderDecodeObjectForValue + 705 16 UIKit 0x000000010609f558 -[UINibDecoder decodeObjectForKey:] + 278 17 UIKit 0x0000000105ecb4b1 -[UIRuntimeConnection initWithCoder:] + 180 18 UIKit 0x000000010609f822 UINibDecoderDecodeObjectForValue + 705 19 UIKit 0x000000010609f9e3 UINibDecoderDecodeObjectForValue + 1154 20 UIKit 0x000000010609f558 -[UINibDecoder decodeObjectForKey:] + 278 21 UIKit 0x0000000105eca6c3 -[UINib instantiateWithOwner:options:] + 1255 22 UIKit 0x0000000106232c40 -[UIStoryboard instantiateViewControllerWithIdentifier:] + 181 23 UIKit 0x0000000106232d93 -[UIStoryboard instantiateInitialViewController] + 69 24 UIKit 0x0000000105b0dfa6 -[UIApplication _loadMainStoryboardFileNamed:bundle:] + 94 25 UIKit 0x0000000105b0e2d6 -[UIApplication _loadMainInterfaceFile] + 260 26 UIKit 0x0000000105b0cb54 -[UIApplication _runWithMainScene:transitionContext:completion:] + 1390 27 UIKit 0x0000000105b09e7b -[UIApplication workspaceDidEndTransaction:] + 188 28 FrontBoardServices 0x000000010b41e754 -[FBSSerialQueue _performNext] + 192 29 FrontBoardServices 0x000000010b41eac2 -[FBSSerialQueue _performNextFromRunLoopSource] + 45 30 CoreFoundation 0x0000000108432a31 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 17 31 CoreFoundation 0x000000010842895c __CFRunLoopDoSources0 + 556 32 CoreFoundation 0x0000000108427e13 __CFRunLoopRun + 867 33 CoreFoundation 0x0000000108427828 CFRunLoopRunSpecific + 488 34 UIKit 0x0000000105b097cd -[UIApplication _run] + 402 35 UIKit 0x0000000105b0e610 UIApplicationMain + 171 36 Develop-InsertViewer 0x00000001055ae752 main + 114 37 libdyld.dylib 0x00000001095a192d start + 1 ) libc++abi.dylib: terminating with uncaught exception of type NSException

如果我在其他类上执行[self appearance]，例如UIToolBar

，也会发生这种情况

任何想法？

Answer 1

外观系统将所有属性瓶颈到单个实现TaggingAppearanceObjectSetterIMP。该实现检查选择器的名称（使用_UIAppearanceTagObjectForSelector）并在关联的对象缓存中查找（存储在__UIAppearanceCustomizedSelectorsAssociationKey中）。如果它不存在，它会调用_TagForSelectorWithAxes来确定映射到该选择器的内容，并更新缓存。

你用自己的运行时技巧踩到了一段相当复杂的运行时技巧。爆炸起来并不令人震惊....：D

基本问题至少是方法的名称必须是setBackgroundColor，而不是swizzled_setBackgroundColor。您可以通过调整实际的实现函数而不是方法来解决这个问题。您可以查看NSNotificationCenter+RNSwizzle.m，了解手动执行此操作的示例。

如果在解决之后你还遇到其他微妙的问题，我不会感到惊讶。我的建议是（好吧，我的建议是“从不混淆生产代码，它太脆弱了”，但是如果你忽略了这个建议......）在Hopper中拉出外观代码并追踪实现，这样你就可以了确保一切都排好。这不是复杂，而Hopper的伪代码模式几乎可以告诉你发生了什么（我花了大约2分钟来计算我在这里发布的内容）。也就是说，这是一个非常棘手的实现细节，它可以在没有警告的情况下轻松更改（导致新的崩溃）。如果你可以不乱晃地做到这一点，我强烈推荐。

对符合UI_APPEARANCE_SELECTOR

1 个答案: