Comparing in objective C - Implicit conversion of 'int' to 'id' is disallowed with ARC

Question

I i'm getting the error "Implicit conversion of 'int' to 'id' is disallowed with ARC" at the line marked with "faulty line". I guess it have something to do with that i'm checking for an integer in an array, that contains objects instead of integers. ``` #import "RandomGenerator.h" @implementation RandomGenerator NSMutableArray *drawnNumbers; -(int) randomNumber:(int)upperNumber { return arc4random_uniform(upperNumber); } -(NSMutableArray*) lotteryNumbers :(int)withMaximumDrawnNumbers :(int)andHighestNumber { for (int i = 1; i <= withMaximumDrawnNumbers; i++) { int drawnNumber = [self randomNumber:andHighestNumber]; if ([drawnNumbers containsObject:drawnNumber]) { //faulty line //foo } } return drawnNumbers; } @end ```

Accepted Answer

NSArrays can only contain objective-c objects. So actually the method containsObject: is expecting an object, not an int or any other primitive type.

If you want to store number inside an NSArray you should pack them into NSNumber objects.

```
NSNumber *someNumber = [NSNumber numberWithInt:3];
```

In your case, if we assume that drawnNumbers is already an array of NSNumbers, you should change the randomNumber: generation to:

```
-(NSNumber*) randomNumber:(int)upperNumber {
    return [NSNumber numberWithInt:arc4random_uniform(upperNumber)];
}
```

And then when picking it up on the lotteryNumbers method, you should:

```
NSNumber *drawnNumber = [self randomNumber:andHighestNumber];
```

Another note would go for the method you defined for lotteryNumbers. You used a really strange name for it, I think you misunderstood how the method naming works in objective-c. You were probably looking for something more like:

```
-(NSMutableArray*) lotteryNumbersWithMaximumDrawnNumbers:(int)maximumDrawnNumbers andHighestNumber:(int)highestNumber;
```

Late edit:

Objective-C now allows a way more compact syntax for creating NSNumbers. You can do it like:

```
NSNumber *someNumber = @(3);
```

And your method could be rewritten as:

```
-(NSNumber*) randomNumber:(int)upperNumber {
    return @(arc4random_uniform(upperNumber));
}
```

Comparing in objective C - Implicit conversion of 'int' to 'id' is disallowed with ARC

Solution

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