iOS Simple Drawing Program

[HarryWorksInc]

I am just creating a simple drawing program, I have been a developer for years now and I know I must be doing something insanely stupid but heres my code,

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
	CGPoint thumbPoint;
	UITouch *thumb = [[event allTouches] anyObject];
	thumbPoint = [thumb locationInView:thumb.view];
	
	UIImageView *newImage = [[UIImageView alloc] initWithFrame:CGRectMake(thumbPoint.x, thumbPoint.y, 17, 17)];
	newImage.image = [UIImage imageNamed:@"BlackDot.png"];
}

I don't know what i'm doing wrong but all this is supposed to do is create a small square on the screen this repeats in the touchesMoved void.

Nothing happens though, help would be much obliged.

 

[robbieduncan]

1) That is a totally insane way to draw a single pixel.

2) You've not added the new view a subview of any visible view so it's not actually on screen anywhere.

 

[HarryWorksInc]

thanks, that worked but how would you do it, if my way is so insane?

 

[robbieduncan]

The reason your way is insane is that you'll end up with so many views that performance will be poor. And there will probably be quite a lot of lag too.

Option 1:

Composite yourself: just create a UIImage and composite your "pixel" image yourself. Downside of this is tracking your pixels and the more you have the longer this will take

Option 2:

Well then re-lock focus on the composited image from last time and composite the new pixel in. This will probably work OK

Option 3:

Do it the "right" way. Create a CGBitmapContext with the correct options and "draw" by simply manipulating the image bytes directly.