Swift4 - Unexpectedly found nil - Setting Image to Button [duplicate] - swift

Question

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Calling reload Sections from AppDelegate
(2 answers)
Closed 4 years ago.
Hi guys I want to make a helper class, which sets all my pictures to my buttons. But always the picture is nil :( Where is my mistake?
class 1 (Where action happens)
class RandomClass {
let imageSetter = ImageSetter()
let mvc = MainViewController()
func actionWhenConnected(){
imageSetter.setButtonImages(nameOfButton: mvc.ConnectingButtonLabel, nameOfImage: "Connection/ConnectionOn", nameOfColor: .green, forStatus: .normal)
}
}
This means when the function is called, the image in my MainViewController should switch to my green Connection On Picture
class 2 (Helper Class)
class ImageSetter{
func setButtonImages(nameOfButton:UIButton, nameOfImage:String, nameOfColor:UIColor, forStatus:UIControl.State){
nameOfButton.setImage(UIImage(named: nameOfImage), for: forStatus)
let origImage = UIImage(named: nameOfImage)
let tintedImage = origImage?.withRenderingMode(.alwaysTemplate)
nameOfButton.setImage(tintedImage, for: .normal)
nameOfButton.tintColor = nameOfColor
}
}
Assets
In my MainViewController it works :(
It seems that RandomClass has no access to assets.xcassets because it doesnt find the name of the image?
SOLVED!
func actionWhenConnected(){
let mvc = UIApplication.shared.keyWindow?.rootViewController as! MainViewController
imageSetter.setButtonImages(nameOfButton:mvc.ConnectingButtonLabel, nameOfImage: "Connection/ConnectionOff", nameOfColor: .red, forStatus: .normal)
}
Big thanks #matt

Answer 1

The problem is this line:
let mvc = MainViewController()
Think about what the phrase MainViewController() does! It creates a new separate second instance of MainViewController. Thus the view never loads from the storyboard, the outlet to the button is never hooked up, and you crash.
What you want is a reference to the actual MainViewController instance whose view already exists in your interface. That is the one with the button you can see.
In my MainViewController it works
Yes, because in MainViewController you know how to get a reference to this instance — you just say self. But even there it wouldn’t work if you said MainViewController().
It seems that RandomClass has no access to assets.xcassets because it doesnt find the name of the image?
Yes it does. It finds the image. What is nil is the button.