CODEWITHSUNDEEP
objective-cios9.2
Prerit Singh Chaudhary
Prerit Singh Chaudhary

Reputation: 21

implicit conversion of int to NSString is disallowed with arc in Objective-C

enter image description here
Could anybody suggest where I'm going wrong?

Upvotes: 0

Views: 5384

Answers (3)

ingconti
ingconti

Reputation: 11666

a more elaborated question. first a quick response:

You cannot call swift plain function from objC. You can call methods but not plain f.

see below:

// swift class:

@objc class Klass: NSObject {

    var a = 100
    
     @objc public func F1()->String{
        return "F1"
    }

    
    @objc public func F2()->NSString{
        return "f2"
    }

}

func myF()->String{
    return "FFF"
}


func myG()->NSString{
    return "GGG"
}

in objC:

@implementation ViewController

- (void)viewDidLoad {

    [super viewDidLoad];
    Klass* k = [Klass new];
    
    NSString * s1 = [k F1];
    NSString * s2 = [k F2];

    s1 = k.F1;
    s2 = k.F2;
    
    NSString * sf = myF(); // ERROR! ... Implicit conversion of 'int' to 'NSString *' is disallowed with ARC
    NSString * sg = myG(); // ERROR!     "      "   "
}

If you add a plain C code (adding includes and so on...)

include "plainFunctions.h"

//file:plainFunctions.c
#include "plainFunctions.h"

int myN()
{
    return 100;
}

You can call:

- (void)viewDidLoad {

    [super viewDidLoad];
    int n = myN();
}

or even:

//h:
char * myC(void);


// objC:
    NSString * fromC = [NSString stringWithCString:myC() encoding: NSUTF8StringEncoding];

Upvotes: 2

Martin Cowie
Martin Cowie

Reputation: 2601

Beware the comma operator. That the message says ... disallowed with ARC is a red herring, the issue here is you're assigning a number to an NSString*.

It's not entirely clear from your screenshot, which I summarise here:

NSString *currurl = (@"https://some-string-%d", 'abcd');

.. where it looks like you're trying to compose an NSString*.

However the compiler is evaluating an expression comprising an NSString*, the comma-operator and a character, where the result is the right hand operand of that comma operator. So it is trying to assign abcd to currurl.

Remember that characters are integer types in C based languages (same in Java), hence the complaint Implicit conversion of 'int' to 'NSString *'

Upvotes: 0

Neha Gupta
Neha Gupta

Reputation: 157

Try writing curl url like this :- 

NSString* curlURL = [NSString stringWithFormat:@"https://api.500px.com/v1/photos?.....rpp=20&page=%d", 123];

Hope given string format helps you.. Thanks

Upvotes: 3

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