Declare String then open string from Path with Cocoa

Question

I've Declared a string Like so

NSString* fileName = [files objectAtIndex:i]; NSLog(fileName);

NSImage* imageFromBundle = [[NSImage alloc] initWithContentsOfFile:fileName];

and want to use that filename to open a file in a different directory. I came up with this

NSImage* imageFromBundle2; imageFromBundle2 = [[NSImage alloc] initWithContentsOfFile:@"/Users/rhaynes/Documents/works4/" filename ];

Any help would be appreciated

Answer 1

Hey Casino,

I'll assume that your fileName string is actually a file name, like "myImage.png". A lot of the Objective-C docs refer to a file name when they really mean file path - so sometimes it's confusing.

What you want to do is create an NSString that represents the complete path to the file you want to load. For instance, you could say:

NSString * path = [NSString stringWithFormat: @"/Users/rhaynes/Documents/works4/%@", fileName];

That line creates a new NSString using the format string and parameters provided (the %@ in the format string indicates that the string value of fileName should be inserted there.) StringWithFormat is a really powerful function, so you should definitely check it out in the docs.

Then you could call initWithContentsOfFile:path, and it should give you the image you want.

Answer 2

NSString* fileName = [files objectAtIndex:i]; NSLog(fileName);

Don't pass non-hard-coded strings as format-string arguments. If they contain format specifiers, you'll get garbage or a crash. (Try this with fileName = @"foo%sbar", for example. Then try it with fileName = @"foo%fbar" for even more fun.)

Your NSLog statement should be:

NSLog(@"%@", fileName);

[I] want to use that filename to open a file in a different directory. I came up with this

NSImage* imageFromBundle2; imageFromBundle2 = [[NSImage alloc] initWithContentsOfFile:@"/Users/rhaynes/Documents/works4/" filename ];

You can only concatenate string literals this way; as you've no doubt seen for yourself, this is a syntax error when one of the strings isn't a literal.

First off, if fileName is actually a pathname, you'll need to use lastPathComponent to get the actual filename. So:

NSString *path = [files objectAtIndex:i];
NSString *filename = [path lastPathComponent];

Then, use stringByAppendingPathComponent: to tack this onto the new superpath.

NSString *desiredFilenamePath = [directoryPath stringByAppendingPathComponent:filename];

Now you have the pathname you wanted to pass to NSImage's initializer.