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"

)

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];

)

{

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);

}

// Default@2x.png

if (resultImage == nil)

{

targetFileName = [imageName2x stringByAppendingPathExtension:imageExt];

targetFilePath = [bundlePath stringByAppendingPathComponent:targetFileName];

resultImage = GetImageAtPath(targetFilePath,2.0f);

}

// Default_2only_@2x.png

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);

}

// Default@1x.png

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)

{

// Default@2x.png

targetFilePath = [mainBundle pathForResource:imageName2x ofType:imageExt];

resultImage = GetImageAtPath(targetFilePath,2.0f);

// Default_2only_@2x.png

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);

}

// Default@1x.png

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;

}