快速使用弱变量或强变量

Question

I wonder when I should use weak and when I should use strong variables.

To make it simple lets say that I will hide my navigation bar when the user scrolls up.

Then I will set up a function to hide the bar once the user is scrolling up. But I can set a boolean value to check if the bar already is hidden, if so then its no need to run the function to hide the navigation bar. And also change that boolean when needed.

So would that kind of variable be a weak or strong one?

weak var isHidden = false
var isHidden = true

Answer 1

Use weak if that object has a life out side that reference.That is if it has a strong reference somewhere else. Use strong , when that particular reference determines the life of that object