Different behaviour of [NSMutableString writeToFile] in iOS7 and iOS8

Question

Here i have demo code for saving NSMutableString in to File (FileName.dat)

NSError* error = nil;
NSMutableString* dat = [[NSMutableString alloc] initWithCapacity:1];
BOOL result = [dat writeToFile:@"FileName.dat" atomically:YES encoding:NSUTF8StringEncoding error:&error];

but i have two different output while rung it in iOS7 and iOS8beta5

Output XCode5+iOS7

Output XCode5+iOS8

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While running it in iOS7 it shows that there in an error in parsing file path, but in iOS8beta5 it crash by saying that [NSFileManager fileSystemRepresentationWithPath:] have nil or empty path.

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Question :
In both SDK iOS8 and iOS7 it take NSError as argument to return error, so i believe that it should return error instead of crashing application
Is apple mansion any changes regarding it, If yes then please give me reference link for the same.

Answer 1

The path you pass to [NSData writeToFile:atomically:] is not complete and should be a full path.

That is normally done by getting the path to the Documents folder and appending that filename.

Answer 2

The problem is your filename, @"FileName.dat", there is no path to the directory to save to. NSFileManager does not do this itself, you'll want to save to the Documents folder normally. Here is the code I usually use:

[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0] stringByAppendingPathComponent:myFileName];