防止文件备份到iCloud和iTunes中
ios5.0
在ios5.0中,不可能设置不备份的数据。如果app支持ios5.0的话,你需要将你不备份的数据放在Caches目录中。iOS会在必要的时候删除Caches目录中的文件,因此你的app需要处理这些文件被删除的情景
ios5.0.1
如果你的app支持ios5.0.1,如果不想将创建的文件或文件夹备份的话,你需要先将数据写道文件中然后调用下面的方法
#import <sys/xattr.h> - (BOOL)addSkipBackupAttributeToItemAtURL:(NSURL *)URL { assert([[NSFileManager defaultManager] fileExistsAtPath: [URL path]]); const char* filePath = [[URL path] fileSystemRepresentation]; const char* attrName = "com.apple.MobileBackup"; u_int8_t attrValue = 1; int result = setxattr(filePath, attrName, &attrValue, sizeof(attrValue), 0, 0); return result == 0; }
ios5.1+
从ios5.1开始,app可以用NSURLIsExcludedFromBackupKey 或者 kCFURLIsExcludedFromBackupKey 文件属性来设置以防止被备份。调用下面的方法即可
- (BOOL)addSkipBackupAttributeToItemAtURL:(NSURL *)URL { assert([[NSFileManager defaultManager] fileExistsAtPath: [URL path]]); NSError *error = nil; BOOL success = [URL setResourceValue: [NSNumber numberWithBool: YES] forKey: NSURLIsExcludedFromBackupKey error: &error]; if(!success){ NSLog(@"Error excluding %@ from backup %@", [URL lastPathComponent], error);
} return success; }
总结所有版本
+(BOOL)addSkipBackupAttributeToItemAtURL:(NSURL *)fileURL { if (![[NSFileManager defaultManager] fileExistsAtPath:[fileURL path]]) { NSLog(@"File %@ doesn't exist!",[fileURL path]); return NO; } NSString *currSysVer = [[UIDevice currentDevice] systemVersion]; if ([currSysVer isEqualToString:@"5.0.1"]) { const char* filePath = [[fileURL path] fileSystemRepresentation]; const char* attrName = "com.apple.MobileBackup"; u_int8_t attrValue = 1; int result = setxattr(filePath, attrName, &attrValue, sizeof(attrValue), 0, 0); NSLog(@"Excluded '%@' from backup",fileURL); return result == 0; } else if (&NSURLIsExcludedFromBackupKey) { NSError *error = nil; BOOL result = [fileURL setResourceValue:[NSNumber numberWithBool:YES] forKey:NSURLIsExcludedFromBackupKey error:&error]; if (!result) { NSLog(@"Error excluding '%@' from backup. Error: %@",fileURL, error); } return result; }