How do I determine what the valid range is for CGPoint on a device when using locationInView of touch events?

UITouch*yourTouchNameHere = [touches anyObject]; CGPoint yourPointNameHere=[touch locationInView:self.view]; 

This automatically means that the touch is on the screen, so any touch-point returned would be valid, but still the code below might help your understanding:

Receive Screen size with: [UIScreen mainScreen].bounds.size

Height of iOSDevice in pixels returned with:

[UIScreen mainScreen].bounds.size.height 

Width of iOSDevice in pixels returned with:

[UIScreen mainScreen].bounds.size.width 

Is the iOSDevice an iPhone with:

if([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPhone){} 

Is the iOSDevice an iPad with:

if([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad){} 

Another stackOverflow question here shows you could also use

Return the entire screen resolution in points (320x400, etc.) with:

CGRect screenBounds = [[UIScreen mainScreen] bounds]; 

Return the screen resolution scale with:

CGFloat screenScale = [[UIScreen mainScreen] scale]; 

Another way to get the pixel width and height with the two above lines included:

CGSize screenSize = CGSizeMake(screenBounds.size.width * screenScale, screenBounds.size.height * screenScale);