This framework is designed to extract resources from zip files without the need to download the entire zip file. The intended use was for jailbroken iDevice projects to extract assets from the various zip files found here: http://mesu.apple.com/assets/com_apple_MobileAsset_SoftwareUpdate/com_apple_MobileAsset_SoftwareUpdate.xml
The easiest way to use it is to drop PZFileBrowser.h and PZFileBrowser.m into your project. It is important to link to libz.dylib as this is required to decompress assets. libz.dylib can be included in a Theos make file by adding:
ProjectName_LIBRARIES = z
Usage:
NSString *zipPath = @"http://appldnld.apple.com/iOS7.1/031-5051.20140630.1zyJC/com_apple_MobileAsset_SoftwareUpdate/be2f8a9534473bd41453e61169b860638d33c8e3.zip";
// Loads the zip files central directory
PZFileBrowser *browser = [PZFileBrowser browserWithPath:zipPath];
// Gets an array containing the paths to all files found in the central directory
// For large zip files allPaths contains too many paths to use NSLog and must be written to a text file for viewing
NSArray *allPaths = [browser getAllPaths];
// If you find the path for the asset you want in allPaths you can use the path to fetch it
NSString *path = @"AssetData/payload/replace/System/Library/PrivateFrameworks/PhotoLibrary.framework/[email protected]";
// Fetches the data using the file path from the remote zip file
NSData *data = [browser getDataForPath:path];The previous example works for well checking if an asset is present during development but can be extremely slow with large zip files due to the need to download the entire zip file's central directory.
In order to get around that it is possible to determine the byte range for a group of assets:
NSString *zipPath = @"http://appldnld.apple.com/iOS7.1/031-5051.20140630.1zyJC/com_apple_MobileAsset_SoftwareUpdate/be2f8a9534473bd41453e61169b860638d33c8e3.zip";
// Loads the zip files central directory
PZFileBrowser *browser = [PZFileBrowser browserWithPath:zipPath];
// In com_apple_MobileAsset_SoftwareUpdate zip files all assets in a folder are grouped in the central directory together based on their absolute path
// These two paths are the first and last paths in PhotoLibrary.framework as determine by -getAllPaths in the previous example
NSString *firstPath = @"AssetData/payload/replace/System/Library/PrivateFrameworks/PhotoLibrary.framework/[email protected]";
NSString *lastPath = @"AssetData/payload/replace/System/Library/PrivateFrameworks/PhotoLibrary.framework/[email protected]";
// Because we know all the assets we want to access are in PhotoLibrary.framework it is now possible to get the range of these assets within the central directory
NSRange range = [browser getByteRangeFromPath:firstPath toPath:lastPath];In the previous example the byte range of the desired assets was determined. This allows for only that range to be parsed allowing for extremely fast fetching of assets from zip files well over one gigabyte.
This is the recommended usage for extracting assets:
NSString *zipPath = @"http://appldnld.apple.com/iOS7.1/031-5051.20140630.1zyJC/com_apple_MobileAsset_SoftwareUpdate/be2f8a9534473bd41453e61169b860638d33c8e3.zip";
// This is initiallized using the byte range determined in the previous example
// Hard coding of the byte range is recommended because com_apple_MobileAsset_SoftwareUpdate zip files are never modified due to older devices relying on them for over-the-air updates
PZFileBrowser *browser = [PZFileBrowser browserWithPath:path byteRange:NSMakeRange(7370041, 3284)];
// Gets an array containing the paths to all files found in within the byte range
NSArray *allPaths = [browser getAllPaths];
NSString *path = @"AssetData/payload/replace/System/Library/PrivateFrameworks/PhotoLibrary.framework/[email protected]";
// Fetches the data using the file path from the remote zip file
NSData *data = [browser getDataForPath:path];Special thanks to planetbeing for https://github.com/planetbeing/partial-zip which this was heavily based on.