Randomizing images while floating up the screen

Question

In my application I am planning on adding balloons that float up the screen and pop when they hit spikes. I need help implementing the balloon floating up the screen and making it randomly generate spawn points. I also need to add code that gradually makes the balloons float faster up the screen and in larger quantities.

Any suggestions of where to find tutorials/ help on this.

Answer 1

1. Set up a int in the .h file, maybe int balloonMovement
2. Link all your balloon images to your .h in between your curly brackets as IBOutlets

i.e. IBOutlet UIImageView *balloon1; IBOutlet UIImageView *balloon2;

1. Set up another int randomPosition and use a random number generator to set positions of balloons on the screen, maybe when user clicks start, or something happens.

You could have this in the viewDidLoad:

RandomPosition = arc4random()%248; //the number of possibilities
RandomPosition = RandomPosition + 36; //the new position 
balloon1.center = CGPointMake(RandomPosition, RandomPosition); //make position

This makes them appear randomly on the screen.

Then, to have them float upward, set up int upMovement; and an NSTimer *movement;, and have it set so every so often, they move upward.

Use the following code to do so:

    movement = [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(moving) userInfo:nil repeats:YES];

This says, every 0.05 seconds, we want to activate the movement.

Then create a method for balloonMovement -- -(void)balloonMovement; in the .h

And fill out its info in the .m -->

-(void)balloonMovement {

    balloon1.center = CGPointMake(balloon1.center.x, balloon1.center.y + upMovement);

}

And another one for the actual moving of the balloon, and set up the conditions that you want them to float upwards, i.e. user cuts string?

-(void)balloonMoving {
     upMovement = upMovement + 0.1 //this will make it gradually faster 

     if (//user cuts string code) {
        [self balloonMovement];
     }
}

This should work. Obviously it's very simple. You will have to customise it. But this should give you the basics. Hope it helped.

One more thing**

To make them change positions as they go up the screen, you'll have to set up a int sideMovement, and add it the same way you did upMovement. But I'll leave that to you to figure out.