Question

I am trying to build a NSURL using a path string. The string looks fine but when I try to put that in an NSURL it gets a bunch of gibberish in it. Here is the code I am using to build up the url:

NSString* path = [[AppSettings instance].contentRootPath stringByAppendingPathComponent: item.fileName];
NSLog(path);
item.contentPath = [NSURL URLWithString:[path stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSLog(item.contentPath.absoluteString);

And here is the log:

2012-07-25 10:28:39.983 mxHub[44036:207] /Users/casey.borders/Library/Application Support/iPhone Simulator/5.0/Applications/C2C1975D-7FAB-4E6C-A091-DC389223CC57/Documents/.content/PREZISTA-PI.pdf

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Answer 1

It’s to do with NSLog, nothing to do with your urls 🙂

Try this :

NSString* path = [[AppSettings instance].contentRootPath stringByAppendingPathComponent: item.fileName];
NSLog(@"%@", path);
item.contentPath = [NSURL URLWithString:[path stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
NSLog(@"%@", item.contentPath.absoluteString);

The first parameter for NSLog is a format string – this tells NSLog that there might be other values to insert into the output (these are the other optional parameters that NSLog takes – for example NSLog(@"%i", 5); would replace the %i with 5).

The NSLog(path); is fine because there aren’t any special formatting characters in the path so it outputs as you would expect.

The second NSLog has % characters in – you added them when you asked to % escape the path 🙂 For example, you replaced the space in ‘Application Support’ with %20.

This means that your url now contains the formatting code %20S (the S is the next character after the space, the first character in the word ‘Support’).

%S is interpreted by NSLog as ‘take the next paramter that I have been given and treat it as a null terminated c-string’.

Unfortunately, you didn’t give NSLog another parameter 🙂 However, NSLog didn’t know that – it just dutifully did as it was told and took the next value on the stack and added it to the output string.

The next value on the stack is garbage which is why your output is garbage!

You can see that the corrupted values appear instead of the spaces in your path – both spaces happen to be followed by an S so NSLog is dumping garbage in two places. That’s why after the first load of garbage you can see ‘upport/iPhone’ and after the second ‘imulator/5.0’ 🙂