逆向iOS SDK -- _UIImageAtPath 的实现（SDK 5.1）

注释过的反汇编代码：http://pan.baidu.com/share/link?shareid=3491166579&uk=537224442

伪代码（不精确，仅供参考）： 

 

NSString* _UICacheNameForImageAtPath(NSString *imageName,NSBundle *bundle); NSString* ProductSuffix(); UIImage* GetImageAtPath(NSString *imageFilePath,CGFloat scale);   NSMutableDictionary *gCacheNameToImageMap =nil; NSMutableDictionary *gImageToCacheNameMap =nil; BOOL __prefer2xImages = NO;   UIImage *_UIImageAtPath(NSString *imageFileName,NSBundle *mainBundle, BOOL shouldForce1xScale) {     // imageFileName = @"Default.png"     if ([imageFileName length] == 0)         return nil;         // bundleIdentifier_imageFileName     NSString *cacheNameOfImage =_UICacheNameForImageAtPath(imageFileName, mainBundle);     UIImage *resultImage = nil;     if (gCacheNameToImageMap !=nil)     {         resultImage = [gCacheNameToImageMapobjectForKey:cacheNameOfImage];         if (resultImage != nil)         {             if (![resultImage _isCached])             {                 [resultImage retain];             }                         [resultImage _setCached:YES];                         return resultImage;         }     }     else     {         gCacheNameToImageMap = [NSMutableDictionarydictionary];         gImageToCacheNameMap = [NSMutableDictionarydictionary];     }         BOOL force1xScale = NO;     if (__prefer2xImages)     {         force1xScale = shouldForce1xScale;     }         NSString *imageExt = [imageFileNamepathExtension];     if ([imageExt length] == 0)     {         imageExt = @"png";     }         NSString *bundlePath = nil;     if (mainBundle != nil)     {         bundlePath = [mainBundle bundlePath];     }         NSString *productSuffix = ProductSuffix();// ~iphone, ~ipad     NSString *imageNameWithoutSuffix = [imageFileNamestringByReplacingOccurrencesOfString:productSuffixwithString:@""];                            // Default     NSString *imageNameWithoutSuffixAndExt = [imageNameWithoutSuffixstringByDeletingPathExtension];     // Default~iphone     NSString *imageNameWithSuffix = [imageNameWithoutSuffixAndExtstringByAppendingString:productSuffix];     // Default@1x     NSString *imageName1x = [imageNameWithoutSuffixAndExtstringByAppendingString:@"@1x"];     // Default@1x~iphone     NSString *imageName1xWithSuffix = [imageName1xstringByAppendingString:productSuffix];     // Default_1only_     NSString *imageName_1only_ = [imageNameWithoutSuffixAndExtstringByAppendingString:@"_1only_"];     // Default_1only_~ipnone     NSString *imageName_1only_WithSuffix = [imageName_1only_stringByAppendingString:productSuffix];         // Default@2x     NSString *imageName2x = [imageNameWithoutSuffixAndExtstringByAppendingString:@"@2x"];     // Default@2x~iphone     NSString *imageName2xWithSuffix = [imageName2xstringByAppendingString:productSuffix];     // Default_2only_@2x     NSString *imageName_2only_2x = [imageNameWithoutSuffixAndExtstringByAppendingString:@"_2only_@2x"];     // Default_2only_@2x~iphone     NSString *imageName_2only_2xWithSuffix = [imageName_2only_2xstringByAppendingString:productSuffix];         NSString *targetFileName =nil;     NSString *targetFilePath =nil;     if (!force1xScale)     {         // Default@2x~iphone.png         targetFileName = [imageName2xWithSuffix stringByAppendingPathExtension:imageExt];         targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];         resultImage = GetImageAtPath(targetFilePath,2.0f);                 // Default_2only_@2x~iphone.png         if (resultImage == nil)         {             targetFileName = [imageName_2only_2xWithSuffix stringByAppendingPathExtension:imageExt];             targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];             resultImage = GetImageAtPath(targetFilePath,2.0f);         }                 // [email protected]         if (resultImage == nil)         {             targetFileName = [imageName2x stringByAppendingPathExtension:imageExt];             targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];             resultImage = GetImageAtPath(targetFilePath,2.0f);         }                 // [email protected]         if (resultImage == nil)         {             targetFileName = [imageName_2only_2x stringByAppendingPathExtension:imageExt];             targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];             resultImage = GetImageAtPath(targetFilePath,2.0f);         }     }         if (resultImage == nil)     {         // Default~iphone.png         targetFileName = [imageNameWithSuffix stringByAppendingPathExtension:imageExt];         targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];         resultImage = GetImageAtPath(targetFilePath,1.0f);                 // Default.png         if (resultImage == nil)         {             targetFileName = [imageNameWithoutSuffixAndExt stringByAppendingPathExtension:imageExt];             targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }                 // Default@1x~iphone.png         if (resultImage == nil)         {             targetFileName = [imageName1xWithSuffix stringByAppendingPathExtension:imageExt];             targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }                 // Default_1only_~ipnone.png         if (resultImage == nil)         {             targetFileName = [imageName_1only_WithSuffix stringByAppendingPathExtension:imageExt];             targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }                 // [email protected]         if (resultImage == nil)         {             targetFileName = [imageName1x stringByAppendingPathExtension:imageExt];             targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }                 // Default_1only.png         if (resultImage == nil)         {             targetFileName = [imageName_1only_ stringByAppendingPathExtension:imageExt];             targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }                 // Default~iphone         if (resultImage == nil)         {             targetFilePath = [bundlePath stringByAppendingPathComponent:imageNameWithSuffix];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }                 // Default         if (resultImage == nil)         {             targetFilePath = [bundlePath stringByAppendingPathComponent:imageNameWithoutSuffixAndExt];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }     }         if (resultImage == nil)     {         if (!force1xScale)         {             // [email protected]             targetFilePath = [mainBundle pathForResource:imageName2x ofType:imageExt];             resultImage = GetImageAtPath(targetFilePath,2.0f);                         // [email protected]             if (resultImage ==nil)             {                 targetFilePath = [mainBundle pathForResource:imageName_2only_2x ofType:imageExt];                 resultImage = GetImageAtPath(targetFilePath,2.0f);             }         }                 // Default.png         if (resultImage == nil)         {             targetFilePath = [mainBundle pathForResource:imageNameWithoutSuffixAndExt ofType:imageExt];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }                 // [email protected]         if (resultImage == nil)         {             targetFilePath = [mainBundle pathForResource:imageName1x ofType:imageExt];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }                 // Default_1only_.png         if (resultImage == nil)         {             targetFilePath = [mainBundle pathForResource:imageName_1only_ ofType:imageExt];             resultImage = GetImageAtPath(targetFilePath,1.0f);         }     }         if (resultImage != nil)     {         [gCacheNameToImageMap setValue:resultImage forKey:cacheNameOfImage];         [gImageToCacheNameMap setValue:cacheNameOfImage forKey:resultImage];         [resultImage _setNamed:YES];         [resultImage _setCached:YES];     }         return resultImage; }