Removing Random Items From NSMutableArray - ios

Question

I have a program where a user enter strings into an NSMutableArray (myArray) via a Text Field. This array is passed into the next view controller where there is a label (myLabel) and two buttons. Printed to the label is a random string from myArray. ButtonA displays a different random string from the array when pressed and ButtonB removes the current string that is printed to the label and then displays a random string from the array to the label.
This is my current solution:
- (void)viewDidLoad {
self.myLabel.text = [self.myArray objectAtIndex:arc4random() % [myArray count]];
-(IBAction)ButtonA:(id)sender {
self.myLabel.text = [self.myArray objectAtIndex:arc4random() % [myArray count]];
}
-(IBAction)ButtonB:(id)sender {
NSInteger index = [myArray indexOfObject: //what goes here?];
[self.myArray removeObjectAtIndex:index];
self.myLabel.text = [self.myArray objectAtIndex:arc4random() % [myArray count]];
}
Is there a way to get the index of the random string displayed and then remove it from the array? I want this to continue doing this until all items from the array have been removed. Thank you

Answer 1

The // what goes here? should simply be self.myLabel.text.
Though it might be better to add an instance variable that saves off the last random index. Then all array index references should be made with that instance variable.
You also have the same line of code to calculate a random number and set a label repeated 3 times. Create a new method for that and call that function from the three places you have it now.

Answer 2

There are two ways you can do this:
The first way is to store the string you got from your random method. You can declare a global variable for this in your class. And I suggest that you always place a block of similar code in another method.
NSString *generatedString;
- (NSString *)generateRandomString
{
generatedString = [self.myArray objectAtIndex:arc4random() % [myArray count]];
return generatedString;
}
Then in your implementation:
- (void)viewDidLoad
{
self.myLabel.text = [self generateRandomString];
}
- (IBAction)buttonA:(id)sender
{
self.myLabel.text = [self generateRandomString];
}
- (IBAction)buttonA:(id)sender
{
[self.myArray removeObject:generatedString];
self.myLabel.text = [self generateRandomString];
}
Another way is to store the index of the string generated:
NSInteger generatedStringIndex;
- (NSString *)generateRandomString
{
generatedStringIndex = arc4random() % [myArray count];
NSString generatedString = [self.myArray objectAtIndex:generatedStringIndex];
return generatedString;
}
Then in your implementation:
- (void)viewDidLoad
{
self.myLabel.text = [self generateRandomString];
}
- (IBAction)buttonA:(id)sender
{
self.myLabel.text = [self generateRandomString];
}
- (IBAction)buttonA:(id)sender
{
[self.myArray removeObject:generatedStringIndex];
self.myLabel.text = [self generateRandomString];
}