Why UIButton can not use KVC to change titleLabel

Question

let newLabel = UILbael()
let button = UIButton()
button.setValue(newLabel, forKeyPath: "titleLabel")

crash info

setValue:forUndefinedKey:]: this class is not key valuecoding-compliant for the key titleLabel

how do it if use kvc ?

This is the same as your previous question. https://stackoverflow.com/questions/51907176/uibutton-set-titlelabel-setvaluenewlabel-forkeypath-titlelabel — Ashley Mills, Sep 08 '18 at 08:54

score 1 · Accepted Answer · answered Sep 05 '18 at 05:42

1

Observe that you can't set the title label directly:

mybutton.titleLabel = UILabel(...)

The reason: it's a read-only property. You have no business trying to substitute a different label inside the button!

answered Sep 05 '18 at 05:42

matt

Yes, it can, if the property supports KVC. But you are trying to write to a read only property. KVC doesn’t let you magically do that. – matt Sep 08 '18 at 21:26

1 Answers1