Returning an NSMutableArray in objective C - ios

Question

I have been trying to work out how to return an MSMutableArray in objective c, I have this code here.
- (NSMutableArray*)generateRandomNumber{
NSMutableArray *unqArray=[[NSMutableArray alloc]init];
int randNum;
int counter = 0;
while (counter< 6) {
randNum = arc4random_uniform(40.0);
if (![unqArray containsObject:[NSNumber numberWithInt:randNum]]) {
[unqArray addObject:[NSNumber numberWithInt:randNum]];
counter++;
}
}
return unqArray;
}
- (IBAction)button:(id)sender {
NSMutableArray *results = [[NSMutableArray alloc]init];
*results = generateRandomNumber();
}
This is my code at the moment, where it says,
NSMutableArray *results = [[NSMutableArray alloc]init];
I get the following errors...
Implicit declaration of function 'generateRandomNumber' is invalid in C99
Assigning to 'NSMutableArray' from incompatible type 'int'
If anybody is willing to show me my mistake and help me out as well as many others I will appreciate it as much as possible.
Thanks to all who help me out!!!

Answer 1

generateRandomNumber is a method, not a C function, so use [self generateRandomNumber] to call it, and you are assigning results incorrectly, so:
results = [self generateRandomNumber];
Alternatively if you want to define it as a C function, use:
NSMutableArray *generateRandomNumber() {
...
}
Also, as pointed-out by #Larme, there is no need to allocate results before assigning it from generateRandomNumber.

Answer 2

- (IBAction)button:(id)sender {
NSMutableArray *results = [[NSMutableArray alloc]init];
results = [self generateRandomNumber];
}
Or more simply:
- (IBAction)button:(id)sender {
NSMutableArray *results = [self generateRandomNumber];
// Do something with this Array
}
Though you should consider a different name for that method as currently it sounds like it is returning one number, not an array of random numbers.

Answer 3

When calling/using a function in Objective-C
it's [self generateRandomNumber]
When you declare a variables it's NSMutableArray *results = [[NSMutableArray alloc]init]; and use if like results = mutableArry, * before it is not needed..
about your problem, you better do it like this:
- (IBAction)button:(id)sender
{
NSMutableArray *results = [self generateRandomNumber];
}
you dont need to allocate anymore, because you are passing an mutable array that is already allocated..

Answer 4

Your method generateRandomNumbers should work as expect the problem is here:
- (IBAction)button:(id)sender {
NSMutableArray *results = [[NSMutableArray alloc]init];
*results = generateRandomNumber();
}
The first thing is that you are creating an unneeded mutable array, second your are trying to substitute the value of the pointer that points to result array, third generateRandonNumber is a method not a function you should call it like [self generateRandomNumber].
Also I would implement a optimization since I'm pretty sure that you are not going to modify the random number array, the returned instance should be an immutable copy.
Here the final code:
- (NSArray*)generateRandomNumber{
NSMutableArray *unqArray=[[NSMutableArray alloc]init];
int randNum;
int counter = 0;
while (counter< 6) {
randNum = arc4random_uniform(40.0);
if (![unqArray containsObject:[NSNumber numberWithInt:randNum]]) {
[unqArray addObject:[NSNumber numberWithInt:randNum]];
counter++;
}
}
return unqArray.copy;
}
- (IBAction)button:(id)sender {
NSArray *results = nil;
results = [self generateRandomNumber];
}

Answer 5

Your generateRandomNumbers method should work with no problem, but in the IBAction there you try to put an INT directly into the array, you need to wrap it in an NSNumber like you have in the other method there

Answer 6

Your method is correct.
What you are doing wrong is here: *results = generateRandomNumber();
There is no need of an * here,because in this way you are trying to assign the pointer address of your array to results object.
Secondly you are trying to call an Objective-C method in C syntax.
So the correct syntax would be: results = [self generateRandomNumber];