将一个文件拷到沙盒

1. NSString *DocumentsDirectory = [[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject] stringByAppendingPathComponent:@"XXX.db"];
2. NSFileManager *fileManager = [[NSFileManager alloc] init];
3. if (![fileManager fileExistsAtPath:DocumentsDirectory]) {
4.     NSString *newFile = [[NSBundle mainBundle] pathForResource:@"XXX.db" ofType:nil];
5.     [fileManager copyItemAtPath:newFile toPath:DocumentsDirectory error:nil];
6. }
7. [fileManager release];