Xcode - differences between simulator and devices on file read

Question

I have tested my app on simulators 4.3, 5.0, 5.1 and 6.0 for iPod, iPad an iPhone. It's working as expected. But on all my devices it doesn't work.

I know that on devices the filenames are case-sensitive. Both the used constant DATA_FILE and the type are lowercase, and the file handle is not nil after opening. As I can see, there is no actual reading after the proper file positioning. Why not?

This is the code, reduced to the minimum to show the problem.

NSLog(@"getData, index = %lu", index);
NSFileHandle *fhIndex = [NSFileHandle fileHandleForReadingAtPath: [[NSBundle mainBundle] pathForResource: DATA_FILE ofType:@"idx"]];

u_char indexData[4];
NSLog(@"index*4 = %lu", (index * 4));
[fhIndex seekToFileOffset: (index * 4)];
unsigned long long test = [fhIndex offsetInFile];
NSLog(@"FilePos = %llu",test);
[[fhIndex readDataOfLength: 4] getBytes: indexData length: 4];
test = [fhIndex offsetInFile];
NSLog(@"FilePos = %llu",test);
NSLog(@"indexData = %i %i %i %i", indexData[0], indexData[1], indexData[2], indexData[3]);

An index (unsigned long) is given to the routine, in this case index=62825. The program make a seek to position index*4 and then reads the next four bytes. On devices, these four bytes are not read!

Debugger output in the simulator:

    2012-10-31 10:46:24.557 program[469:12003] getData, index = 62825
    2012-10-31 10:46:24.559 program[469:12003] index*4 = 251300
    2012-10-31 10:46:24.559 program[469:12003] FilePos = 251300
    2012-10-31 10:46:24.580 program[469:12003] FilePos = 251304
    2012-10-31 10:46:24.581 program[469:12003] indexData = 0 73 130 174

... and on the devices:

    2012-10-31 10:41:57.776 program[2942:907] getData, index = 62825
    2012-10-31 10:41:57.780 program[2942:907] index*4 = 251300
    2012-10-31 10:41:57.782 program[2942:907] FilePos = 251300
    2012-10-31 10:41:57.783 program[2942:907] FilePos = 251300
    2012-10-31 10:41:57.784 program[2942:907] indexData = 248 10 18 0

As you can see in the output on devices, the file position is not changed after the read, that means, there was actually no read!

Now I have checked the fileSize of that file. In the simulator I get 283.020 (that's the correct size), but on devices I get only 220.024 as the size. Because I set the filepos beyond the end, there is no reading. I've deleted the App from my device and installed again. Same result, same bad filesize. I've deleted the file reference in Xcode and added again. Same result! Why I get the wrong filesize on a device but not in the simulator? Any idea? — thpitsch, Oct 31 '12 at 07:02

score 0 · Answer 1 · answered Nov 01 '12 at 03:16

0

Wrong filesize has guided me in the right direction. After deleting the Build directory the program is now working on simulators and devices.

answered Nov 01 '12 at 03:16

thpitsch

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Xcode - differences between simulator and devices on file read

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