Unable to use println() command in Xcode

Question

I am following an online tutorial on how to build apps with Xcode. The video shows how to make a button and connect it to code to print out a statement. I have copied the code from the video 100% but it is not working. I have a more updated version so is there something I need to do differently. I am using Xcode 6.4 and the video was using 6.0. This is my code:

- (IBAction) showFunFact() {
    println("You pressed me!")
}
// Error: Expected method Body
// Error: Semantic issue, Implicit declaration of function 'println' is invalid in C99
// Parse Issue: Expected ';' after expression

These are the three errors I am receiving but I think the other 2 are due to the fact that the program dose not recognise the println command. Anyone know how to fix this!?

pbush25 · Accepted Answer · 2015-07-29 15:46:25Z

6

The reason this isn't working is because the function should be declared like so:

@IBAction func showFunFact() {
    println("You pressed me!")
}

The function you have posted above looks like an Objective-C function, so make sure either that a) your file is not an Objective-C file, or b) if you were trying to use Objective-C, then println() won't work because it's not a method defined in Objective-C. In that case, the appropriate method would be NSLog(@"You pressed me!");

edited Jul 29, 2015 at 15:46

answered Jul 29, 2015 at 15:40

pbush25

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1 Comment

Jack Hayton Over a year ago

Thank you for clarifying this, I had accidentally selected to use Objective-C instead of swift. It works now!

Sami Kuhmonen · Accepted Answer · 2015-07-29 15:40:04Z

2

You are using println in Objective-C code. It is a Swift function, so you have to create a Swift file for that.

In Objective-C you could use NSLog(@"boo!");

answered Jul 29, 2015 at 15:40

Sami Kuhmonen

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Comments

John · Accepted Answer · 2015-07-29 15:46:21Z

0

xcode will compile many different type of languages - from swift to C++ to objective C and so on.

I am going through a similar phase and can tell you that many of the tutorials I find online are now irrelevant because antiquated. I would recommend Stanford's CS 193P lectures which are refreshed every year and use the latest language / compiler so you can always follow along. (Lectures & docs aval for free in itunesU)

answered Jul 29, 2015 at 15:46

John

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