macOS Multiple values from a function with Cocoa - Obj C

[apffal]

I know it's possible to return two or more values from a function using Cocoa - Objective C.
Can someone give me a code example, for getting integer and/or NSString values ?
Thanks in advance

 

[robbieduncan]

You can only return a single value, either a primitive type or an object from a function. But using an object you can return multiple values by encapsulating them in the object. The simplest method would be to return a NSDictionary using pre-defined keys.

#define STRING_KEY @"string"
#define NUMBER_KEY @"number"

-(NSDictionary *) myMethod
{
....
NSMutableDictionary *toReturn = [NSMutableDictionary dictionary];
[toReturn setObject:myNSString forKey:STRING_KEY];
[toReturn setObject:myNSNumber forKey:NUMBER_KEY];
return toReturn;
}

....

NSDictionary *return = myMethod;
stringReturned = [return objectForKey:STRING_KEY];
nsNumberReturned = [return objectForKey:NUMBER_KEY];

 

[apffal]

Gives me syntax errors, before "return", on three last lines of code.
What's wrong ?

 

[robbieduncan]

I've no idea: I just typed it straight into here: you're meant to look at it, understand the concept and apply that to your problem, not simply copy and paste it: that's not programming at all.

 

[apffal]

I've used the code like this

#import "Calc.h"
#define STRING_KEY @"string"

@implementation Calc

-(NSDictionary *) calcDias {

-----------
NSMutableDictionary *toReturn = [NSMutableDictionary dictionary];
[toReturn setObject:final_1 forKey:STRING_KEY];
[toReturn setObject:final_2 forKey:STRING_KEY];
return toReturn;
}

- (IBAction)calc:(id)sender { 

calc = [[Calc alloc]init]; 	

NSDictionary *return = calcDias;
final_1 = [return objectForKey:STRING_KEY];
final_2 = [return objectForKey:STRING_KEY];

--------
}

and get the syntax errors on these 3 lines

NSDictionary *return = calcDias;
final_1 = [return objectForKey:STRING_KEY];
final_2 = [return objectForKey:STRING_KEY];

I' ve defined "final_1" and "final_2" as NSString.
Can you help ?

 

[Cromulent]

I've used the code like this

#import "Calc.h"
#define STRING_KEY @"string"

@implementation Calc

-(NSDictionary *) calcDias {

-----------
NSMutableDictionary *toReturn = [NSMutableDictionary dictionary];
[toReturn setObject:final_1 forKey:STRING_KEY];
[toReturn setObject:final_2 forKey:STRING_KEY];
return toReturn;
}

- (IBAction)calc:(id)sender { 

calc = [[Calc alloc]init];     

NSDictionary *return = calcDias;
final_1 = [return objectForKey:STRING_KEY];
final_2 = [return objectForKey:STRING_KEY];

--------
}

and get the syntax errors on these 3 lines

NSDictionary *return = calcDias;
final_1 = [return objectForKey:STRING_KEY];
final_2 = [return objectForKey:STRING_KEY];

I' ve defined "final_1" and "final_2" as NSString.
Can you help ?

What is the syntax error you are getting? It should be pretty clear from the error what the problem is if you sit down and think about it. Better start learning how to debug your code now, it is an important skill to have 🙂.

 

[apffal]

The error I get ("syntax error before return") is not exactly very clear and explicit - and if I could understand it by myself, certainly would not ask more questions.
Thank you, anyway

 

[yoavcs]

I'd think you'd need something like:

NSDictionary *return = [self calcDias];

seeing as how calcDias is an instance method

 

[ldmbouge]

I've used the code like this

#import "Calc.h"
#define STRING_KEY @"string"

@implementation Calc

-(NSDictionary *) calcDias {

-----------
NSMutableDictionary *toReturn = [NSMutableDictionary dictionary];
[toReturn setObject:final_1 forKey:STRING_KEY];
[toReturn setObject:final_2 forKey:STRING_KEY];
return toReturn;
}

- (IBAction)calc:(id)sender { 

calc = [[Calc alloc]init]; 	

NSDictionary *return = calcDias;
final_1 = [return objectForKey:STRING_KEY];
final_2 = [return objectForKey:STRING_KEY];

--------
}

and get the syntax errors on these 3 lines

NSDictionary *return = calcDias;
final_1 = [return objectForKey:STRING_KEY];
final_2 = [return objectForKey:STRING_KEY];

I' ve defined "final_1" and "final_2" as NSString.
Can you help ?

Easy... you can't call a local variable "return". "return" is a reserved word in C...

Hope that helps,

--
Laurent

 

[cazlar]

Also, I may be wrong, but aren't you storing both final_1 and final_2 under the same key? So really you should have 2 keys!