objective c NSURL may not respond to +initFileURLWithPath

Question

I have two lines of code in the applicationDidFinishLaunching function:

NSString *targetFilePath = @"/Users/bob/Documents/About_Stacks.pdf";
NSURL *targetFileURL = [NSURL initFileURLWithPath:targetFilePath];

and I am getting the warning (title) in the second line...

I have no idea what I am doing wrong. This is an absurdly simply application... I have read other posts about reordering methods, but I am using classes provided by NS, nothing of my own.

Any advice would be much appreciated.

Thanks.

Answer 1

The warning is normal as the method initFileURLWithPath is an instance method and not a class method. The proper way to use it is:

NSString *targetFilePath = @"/Users/bob/Documents/About_Stacks.pdf";
NSURL *targetFileURL = [[NSURL alloc] initFileURLWithPath:targetFilePath];

Answer 2

You have to alloc an NSURL first.

NSURL *targetFileURL = [[NSURL alloc] initFileURLWithPath:targetFilePath];

If the method starts with "init", it means it should be called on an allocated instance, not on the class itself.

Answer 3

initFileURLWithPath: is an instance method, not a class method, so you have to create an instance of the class first with alloc. So:

NSString* targetFilePath = @"/Users/bob/Documents/About_Stacks.pdf";
NSURL* targetFileURL = [[NSURL alloc] initFileURLWithPath:targetFilePath];

If you want to use the convenience method, use fileURLWithPath:, so:

NSURL* targetFileURL = [NSURL fileURLWithPath:targetFilePath];

Answer 4

I think the problem is the NSURL has to created first using alloc . Just declaring it will not work.

Also I think you will need to release it later, otherwise there will be a potential leak.

 NSURL *targetFileURL = [[NSURL alloc] initFileURLWithPath:targetFilePath];

//do some stuff

[targetFileURL release ];