Question

I am getting confused with how to handle Integers in Objective C.

If I define the following:

NSInteger i = 6;
NSLog(@"%d", i);

I expect it to print 6 to the console.

however I have an NSInteger within an object which is obviously reference by a pointer so I get very difference results.

For example:

@interface Section : NSObject {
NSInteger Id;
}

@property (nonatomic, assign) NSInteger Id;

Please assume this has been synthesized in the implementation.

I create the object set its value and access it again as follows:

Section *section = [[Section alloc] init];
section.Id = 6;

NSMutableArray *sections = [[NSMutableArray alloc] init];
[sections addobject:section];

Section *sectionB = [setions objectAtIndex:0];
NSLog(@"%d",  sectionB.Id);

This has the strange effect of printing the memory address ie a number like 5447889. Why can I not just get the value?

I have tried using:

NSInteger sid = [[section Id]integerValue];

But I then get the warning Invalid receiver type ‘NSInteger’ and sometime get an error Program received signal: “EXC_BAD_ACCESS”.

I would really like to know how to handle Integers, or any values for that matter properly.

Many Thanks

Answer 1

Think I found the answer to my own question. Setting the value of an NSInteger to a value of say 6 is fine. The problem I have is I am setting it to the value returned from a Json string using the following:

NSInteger i = [jsonResult objectForKey:@"Id"];

which should be:

NSInteger i = [[jsonResult objectForKey:@"Id"] integerValue];

I have not tested this but makes sense based on what DarkDust said about integerValue taking an object and not an Integer.

Thanks for your input.