iPhone是否保存升级时删除的数据?
我在app store中有一个应用程序,刚收到一个用户的消息,告诉我在升级到新版本的应用程序时,他们保存的数据都消失了 在iphone上保存数据是否存在明显错误的方法,在将应用升级到新版本时会导致数据丢失 下面是我用来加载和保存的代码,它在开发机器上运行良好。这样做不对吗iPhone是否保存升级时删除的数据?,iphone,load,save,upgrade,Iphone,Load,Save,Upgrade,我在app store中有一个应用程序,刚收到一个用户的消息,告诉我在升级到新版本的应用程序时,他们保存的数据都消失了 在iphone上保存数据是否存在明显错误的方法,在将应用升级到新版本时会导致数据丢失 下面是我用来加载和保存的代码,它在开发机器上运行良好。这样做不对吗 - (bool) saveData:(NSData*) data toFile:(NSString*) filename { NSError* error; NSFileManager *fileMgr =
- (bool) saveData:(NSData*) data toFile:(NSString*) filename
{
NSError* error;
NSFileManager *fileMgr = [[[NSFileManager alloc] init] autorelease];
NSString *docsDir = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
NSString* filePath = [docsDir stringByAppendingPathComponent:filename];
NSString* validMarkerPath = [docsDir stringByAppendingPathComponent:[filename stringByAppendingString:@".val"]];
NSString* backupPath = [docsDir stringByAppendingPathComponent:[filename stringByAppendingString:@".bak"]];
// If the file exists and is marke valid, copy it over the backup.
if([fileMgr fileExistsAtPath:filePath] && [fileMgr fileExistsAtPath:validMarkerPath])
{
if([fileMgr fileExistsAtPath:backupPath])
{
if(![fileMgr removeItemAtPath:backupPath error:&error])
{
NSLog(@"Error: SafeFileManager: Could not remove backup file %@: %@", backupPath, [error localizedDescription]);
}
}
if(![fileMgr moveItemAtPath:filePath toPath:backupPath error:&error])
{
NSLog(@"Error: SafeFileManager: Could not move %@ to %@: %@", filePath, backupPath, [error localizedDescription]);
}
}
// Remove the "valid" marker file, if present.
if([fileMgr fileExistsAtPath:validMarkerPath])
{
if(![fileMgr removeItemAtPath:validMarkerPath error:&error])
{
NSLog(@"Error: SafeFileManager: Could not remove validation file %@: %@", validMarkerPath, [error localizedDescription]);
}
}
// Save the new file.
if(![data writeToFile:filePath options:NSAtomicWrite error:&error])
{
NSLog(@"Error: SafeFileManager: Could not save to %@: %@", filePath, [error localizedDescription]);
return NO;
}
// If we succeeded, save the "valid" marker file.
NSData* markerData = [NSData dataWithBytes:"0" length:1];
if(![markerData writeToFile:validMarkerPath options:NSAtomicWrite error:&error])
{
NSLog(@"Error: SafeFileManager: Could not save validation file %@: %@", validMarkerPath, [error localizedDescription]);
return NO;
}
return YES;
}
- (NSData*) loadDataFromFile:(NSString*) filename
{
NSError* error;
NSFileManager *fileMgr = [[[NSFileManager alloc] init] autorelease];
NSString *docsDir = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"];
NSString* filePath = [docsDir stringByAppendingPathComponent:filename];
NSString* validMarkerPath = [docsDir stringByAppendingPathComponent:[filename stringByAppendingString:@".val"]];
// If the file isn't valid, we'll try to load the backup.
if(![fileMgr fileExistsAtPath:validMarkerPath])
{
filePath = [docsDir stringByAppendingPathComponent:[filename stringByAppendingString:@".bak"]];
}
NSData* data = nil;
@try
{
data = [NSData dataWithContentsOfFile:filePath options:NSUncachedRead error:&error];
if(nil == data)
{
NSLog(@"Error: SafeFileManager: Could not load from %@: %@", filePath, [error localizedDescription]);
}
}
@catch (NSException * e)
{
NSLog(@"Error: SafeFileManager: Could not load from %@: %@", filePath, [e description]);
data = nil;
}
return data;
}
为了回答我自己的问题,这段代码确实有一个写入孔,其中备份文件和标记文件被删除,这将导致加载失败
现在,我选择了一种更简单(如果不是更暴力的话)的方法,即简单地保存文件,然后保存备份。加载时,它会尝试主文件,如果出现任何错误,它会尝试使用备份文件执行相同的加载例程。回答我自己的问题,此代码确实有一个写入孔,其中备份文件和标记文件被删除,这将导致加载失败 现在,我选择了一种更简单(如果不是更暴力的话)的方法,即简单地保存文件,然后保存备份。加载时,它会尝试主文件,如果出现任何错误,它会尝试使用备份文件执行相同的加载例程