[原]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)

returnnil;

// 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 = [imageFileName pathExtension];

if ([imageExt length] == 0)

{

imageExt = @"png";

}

NSString *bundlePath = nil;

if (mainBundle != nil)

{

bundlePath = [mainBundle bundlePath];

}

NSString *productSuffix = ProductSuffix();// ~iphone, ~ipad

NSString *imageNameWithoutSuffix = [imageFileName stringByReplacingOccurrencesOfString:productSuffix withString:@""];

// Default

NSString *imageNameWithoutSuffixAndExt = [imageNameWithoutSuffix stringByDeletingPathExtension];

// Default~iphone

NSString *imageNameWithSuffix = [imageNameWithoutSuffixAndExt stringByAppendingString:productSuffix];

// Default@1x

NSString *imageName1x = [imageNameWithoutSuffixAndExt stringByAppendingString:@"@1x"];

// Default@1x~iphone

NSString *imageName1xWithSuffix = [imageName1x stringByAppendingString:productSuffix];

// Default_1only_

NSString *imageName_1only_ = [imageNameWithoutSuffixAndExt stringByAppendingString:@"_1only_"];

// Default_1only_~ipnone

NSString *imageName_1only_WithSuffix = [imageName_1only_ stringByAppendingString:productSuffix];

// Default@2x

NSString *imageName2x = [imageNameWithoutSuffixAndExt stringByAppendingString:@"@2x"];

// Default@2x~iphone

NSString *imageName2xWithSuffix = [imageName2x stringByAppendingString:productSuffix];

// Default_2only_@2x

NSString *imageName_2only_2x = [imageNameWithoutSuffixAndExt stringByAppendingString:@"_2only_@2x"];

// Default_2only_@2x~iphone

NSString *imageName_2only_2xWithSuffix = [imageName_2only_2x stringByAppendingString: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)

{

[gCacheNameToImageMapsetValue:resultImage forKey:cacheNameOfImage];

[gImageToCacheNameMapsetValue:cacheNameOfImage forKey:resultImage];

[resultImage _setNamed:YES];

[resultImage _setCached:YES];

}

return resultImage;

}