Reading byte array from a file in Objective C

Question

I try to read a file with byte data.

My file reading code is

    NSString *filepath=[[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"PATH.dat"];    
    NSLog(@"\n\nthe string %@",filepath);
    NSData *fileData = [NSData dataWithContentsOfFile: filepath];
    char *fileBytes = (char *)[fileData bytes];
    NSUInteger length = [fileData length];
    NSLog(@"length %lu", (unsigned long)length);
    NSUInteger index;
    for (index = 0; index<length; index++)
    {
        char aByte = fileBytes[index];
        NSLog(@"byte %d", aByte);
    }

The following outputs show that file path is ok, but length is 0.

the string /var/containers/Bundle/Application/6D84F701-BC0E-43AD-8FD8-1F0083CE1F84/ProductName.app/PATH.dat
2017-12-22 17:54:18.746773+0800 ProductName[8704:2173252] length 0

What is wrong with my file reading?

EDIT:

if([[NSFileManager defaultManager] fileExistsAtPath: filepath])
        NSLog(@"fileexist");

Could you check before hand if [[NSFileManager defaultManager] fileExistsAtPath: filepath] returns true? If you added yourself the file into your bundle, what about doing: NSString *filepath= [[NSBundle mainBundle] pathForResource:@"PATH" ofType:@"dat"];? — Larme
– Larme, Commented Dec 22, 2017 at 10:09
@Larme I added as in EDIT. But there is no output as fileexist. That means file doesn't exist? I put file as right click to project / Add file to project option. — batuman
– batuman, Commented Dec 22, 2017 at 10:26
Check the target membership: stackoverflow.com/questions/10247680/… — Larme
– Larme, Commented Dec 22, 2017 at 10:27
Y I checked in Build Phase / Copy Bundle Resources. I found the file there. — batuman
– batuman, Commented Dec 22, 2017 at 10:33
Yes it works. Thank you. My problem is misspelled in file name. — batuman
– batuman, Commented Dec 22, 2017 at 11:30

JoGoFo · Accepted Answer · 2017-12-22 11:24:11Z

3

Try getting the path of your file using this instead:

NSString *filepath = [[NSBundle mainBundle] pathForResource:@"FILENAME" ofType:@"dat"];

If that still doesn't work, try:

NSURL *fileUrl = [NSURL fileURLWithPath:filepath];
NSData *fileData = [NSData dataWithContentsOfURL:fileUrl];

answered Dec 22, 2017 at 11:24

JoGoFo

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