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iOS Objective-C Basics (Retired) Beyond the Basics Primitive Data Types

Shaun Kelly
Shaun Kelly
5,648 Points
Posted by Shaun Kelly
Shaun Kelly
5,648 Points

Format Arguments?

I have an NSInteger and when I print out the value there is an error that says. Values of type 'NSInteger' should be used as format arguments; add an explicit cast to 'long' instead.

My "number" variable is only a small number of 10, why do I need to change it to a long? I thought a long was just another data type but allocates more memory because it a bigger number ? And another question, what is a format argument ? 

 NSInteger number = 10;

 NSLog(@"%d", number);
Damien Watson
Damien Watson
27,419 Points
Damien Watson
Damien Watson
27,419 Points

For your code example above, you can use the three ` followed by 'objc' to colorise.

2 Answers

Damien Watson
Damien Watson
27,419 Points
Damien Watson
Damien Watson
27,419 Points

Hey Shaun,

On OSX 64bit an NSInteger is defined as a long, so when you try to format into a string, you need to use the %ld as below. I have been coming across this a lot myself lately and still trying to figure it out.

NSInteger number = 10;
NSLog(@"%ld", (long)number);

Format arguments are I believe the '%?' inside a string which controls the format of the element. eg.

int abc = 10;
NSString *def = @"Hey";
CGFloat myFloat = 1.23;

NSLog(@"%d, %@, %0.2f", abc, def, myFloat);
Brenden Konnagan
Brenden Konnagan
16,858 Points
Brenden Konnagan
Brenden Konnagan
16,858 Points

you are correct... you have to use the correct string format specifier and cast it to a long since NSInteger is a long.

Here is Apple's Documentation:Documentation

Shaun Kelly
Shaun Kelly
5,648 Points
Shaun Kelly
Shaun Kelly
5,648 Points

but the value of the NSInteger is 10 in this case. 'long' is only for big number though ? confused

Brenden Konnagan
Brenden Konnagan
16,858 Points
Brenden Konnagan
Brenden Konnagan
16,858 Points

The value you set it to isn't what makes it a "long" but the type. Much like Double can be assigned 10 but it is still a double.

Suppose:

var numInt: Int = 10

// num is an Int

var numDouble: Double = 10.0

// numDouble is a Double

Both values are "10" but what makes them different is the type it was defined as.

Given the above example your correct that the value is "10" but it is of type NSInteger which the computer knows is a long.