Iphone 在我的设备中写入NSData时出现问题

有人能解释一下为什么我的代码不起作用吗

//get the documents directory:
NSArray *paths = NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];


//make a file name to write the data to using the
//documents directory:
NSString *fullFileName = [NSString stringWithFormat:@"%@/subscriptions", documentsDirectory];
[dataReply writeToFile:fullFileName atomically:NO];




NSData *getData=[[NSData alloc]initWithContentsOfFile:fullFileName];

事实上，如果我尝试

NSString *string = [[NSString alloc] initWithData:getData encoding:NSASCIIStringEncoding];

而如果我加载我的数据而不将其保存到我的设备，它就会工作！（所以我确信我的数据不是空的）

试试这个

NSArray *paths = NSSearchPathForDirectoriesInDomains
(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];


//make a file name to write the data to using the
//documents directory:
NSString *fullFileName = [NSString stringWithFormat:@"%@/subscriptions", documentsDirectory];
[dataReply writeToFile:fullFileName atomically:NO];


Nsdata *getData=[fullFileName dataUsingEncoding:NSUTF8StringEncoding];

定义“作品”。定义“不起作用”。