Passing an float value to another ViewController - ios

Question

I have 2 controllers and i would like to send a float from LevelViewController to ViewController. But it always sends it as 0 (zero). Here is my LevelViewController.m
ViewController *inGame = [[ViewController alloc] init];
enemySpeedShouldBe = 0.800f - 0.07f * levelSelected;
inGame.enemySpeed = enemySpeedShouldBe;
Where levelSelected and enemySpeedShouldBe are also floats.
NSLog(#"%f", levelSelected) gives me the correct value (1.0, 2.0 etc.), but when I send it to ViewController, it's equal to 0.
Here is my ViewController.h
#property (nonatomic) float enemySpeed;
I've read about this issue but I couldn't find any way to make it work.
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here is my enemy millisecond counter methods in "ViewController.m"
-(void)enemyStartCounter{
enemyMs += 0.001;
if(enemyMs > enemySpeed){ // i use 'enemySpeed' nowhere except here
[enemyTimer invalidate];
[fire setHidden:YES];
[self enemyFired];
}
}
-(void)enemyCounter{
enemyMs = 0;
enemyTimer = [NSTimer scheduledTimerWithTimeInterval:0.001/1.0 target:self selector:#selector(enemyStartCounter) userInfo:nil repeats:YES];
}
and my button touchup inside action method in "LevelViewController.m"
- (void)didTapLevel:(UIButton *)buttonn{
levelSelected = (float)buttonn.tag + 1.0f ;
ViewController *inGame = [[ViewController alloc] init];
enemySpeedShouldBe = 0.800f - (0.07f * levelSelected);
inGame.enemySpeed = enemySpeedShouldBe;
[self performSegueWithIdentifier:#"1player" sender:self];
}

Answer 1

At some point in your code you are creating this instance of ViewController, configuring it with a value for enemySpeed, and then probably throwing it away.
Somewhere else, another instance is being created. This instance isn't configured, but you're calling enemyStartCounter on it, so it logs a zero.
You need to ensure that you understand what instances of each class you have and how they're being used. Your view controller could be created from a Storyboard segue, in this case you need to get a reference to it by intercepting the segue using prepareForSegue:sender:.
This code creates 2 different instances:
- (void)didTapLevel:(UIButton *)buttonn{
ViewController *inGame = [[ViewController alloc] init]; // create first instance
inGame.enemySpeed = enemySpeedShouldBe;
[self performSegueWithIdentifier:#"1player" sender:self]; // create second instance
}
So what you should be doing is:
- (void)didTapLevel:(UIButton *)buttonn{
[self performSegueWithIdentifier:#"1player" sender:self]; // create single instance
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
ViewController *inGame = (ViewController *)[segue destinationViewController]; // get single instance
inGame.enemySpeed = enemySpeedShouldBe;
}

Answer 2

I prefer to create a NSNumber property to do this:
#property (strong, nonatomic) NSNumber *enemySpeed; // in your viewController
// passing the parameter
inGame.enemySpeed = [NSNumber numberWithFloat:(0.800f - 0.07f * levelSelected)];
Then if you pass the property between the controllers you can do this :
NSLog(#"%f", [enemySpeed floatValue]);