Collision Detection and gravity help

[Anonymous Username]

I gave a Uiimage view gravity, its pretty cool to watch it fall down the screen for three seconds but how do I make ground for the square to fall on?

My code

@synthesize velocity , gravity, gameLoop, block, ground;



- (void)viewDidLoad {
    [super viewDidLoad];
	
	
	gravity = CGPointMake(0, 0.2);
	
	[NSTimer scheduledTimerWithTimeInterval: 1.0/60 target:self selector:@selector(gameState) userInfo:nil repeats:YES];
	
}


- (void)gameState {

	velocity.y += gravity.y;
	block.center = CGPointMake(block.center.x +velocity.x,block.center.y +velocity.y );
}

[rocotilos]

- (void)gameState {

if (block.frame.origin.y+black.frame.size.height<=self.view.frame.height) {
	velocity.y += gravity.y;
	block.center = CGPointMake(block.center.x +velocity.x,block.center.y +velocity.y );

} else {
  // reached bottom and disable timer or do whatever
}

}

[Anonymous Username]

Uhmm I'm not sure what you were trying to tell me but I figured it out a different way.

	if (CGRectIntersectsRect(block.frame, ground.frame)) 
{
		
		{
			if (block.center.y < ground.center.y) 
			{
				if (velocity.y > 0) 
				{
					velocity.y = 0;
					gravity.y = 0;
				}
			
			}
		}		
	}

but now I have a new problem. I have an IBAction/button called jump,

- (IBAction)pressJump 
{
	velocity.y = -2;
}

when I press it after the block hits the ground it floats up and gravity will never bring it down, when I press it before the block hits the ground gravity will pull it down until it hits the ground, and then gravity stops working.