Creating randomly generated horizontal flying labels - ios

Question

I would like to add a feature to my app that involves labels with different keywords flying horizontally across the view. Ideally, I would like this to be done with an array of words, that are randomly selected to fly across the screen at different velocities and in 3-4 different positions (vertically) on the screen.
I have been doing some research, and maybe I am searching for the wrong thing, but I can't find much advice to get an idea of where I should start. I am only able to find how to move sprites to random areas of a view.
I would like to have more to show, but unfortunately the only code I have so far is as follows:
func generateWords() {
let keyWordArray = ["Word 1", "Word 2", "Word 3", "Word 4", "Word 5"]
for _ in 1...5 {
let randomIndexWords = Int(arc4random_uniform(UInt32(keyWordArray.count)))
}
}
How can I randomly generate multiple labels, at different vertical positions, that fly at different speeds across the screen and then disappear? This would need to happen infinitely until the view is closed by the user.
Thanks!

Answer 1

You want to first get the screen height:
CGFloat height;
height = [[UIScreen mainScreen] bounds].size.height;
You can then decide on the vertical position yourself i.e if you have ten labels divide the height by ten then increment up. To animate the labels you need to place the frame off the screen on one side and then place it on the opposite side. You can animate a UIView, in this example the initial label frame is (someXOffTheScreenOnTheRight, someY, widthOfLabel, HeightOfLabel) :
[UIView animateWithDuration:0.8 delay:0 options:0 animations:^{
[self.view addSubview:label];
label.frame=CGRectMake(-10, someY, widthOfLabel, heightOfLabel);
} completion:^(BOOL finished){
[label removeFromSuperview];
}];
This will animate the label from right to left. You can tweak the speed by changing the duration.
Of course if you want to use random Y coords then use the arc4random method.
That should be enough to get you going..