在预期返回'UIFont？'的函数中缺少返回？

Question

I have a custom UITextfield in swift called COSTextField. It is something like

class COSTextField: UITextField {
    func customFont() -> UIFont? {
        if let font = self.font {
            return UIFont(name: kCOSFontRegular, size: font.pointSize)
        }
    }
}

I am trying to extend this COSTextField class and override the customFont method. My new class looks like

class COSTextFieldLight: COSTextField { 
    override func customFont() -> UIFont? {
        if let font = self.font {
            return UIFont(name: kCOSFontLight, size: font.pointSize)
        }
    }
}

When I try to compile this, I get an error Missing return in a function expected to return 'UIFont?' . If I add a return nil statement at the end of my override function, I get an error Non-void function should return a value

What am I doing wrong?

Answer 1

Add return nil just after the if let branch:

class COSTextField: UITextField {
    func customFont() -> UIFont? {
        if let font = self.font {
            return UIFont(name: kCOSFontRegular, size: font.pointSize)
        }
        return nil
    }
}

class COSTextFieldLight: COSTextField {
    override func customFont() -> UIFont? {
        if let font = self.font {
            return UIFont(name: kCOSFontLight, size: font.pointSize)
        }
        return nil
    }
}

That way, if the if let condition fails, your function will return nil.