Implicit declaration of function 'setAsPrevious' is invalid in c99

Question

For some reason I keep getting the warning "Implicit declaration of function 'setAsPrevious' is invalid in c99" when I attempt to call either of these methods. This warning turns into an error when I try to run the xcode project.

I have looked online, at other questions, and really everywhere I can find but I'm not finding what's wrong. I'm sure it's simple so if someone could just save me days of searching for the simple and point it out to me, I would be very grateful.

- (void)setAsPrevious:(UIView*)thisView {
    [previous removeFromSuperview];
    thisView.accessibilityFrame = CGRectMake(0.0, 0.0, 200.0, 100.0);
    previous = thisView;
}

- (void)setAsCurrent:(UIView*)thisView {
    setAsPrevious(current);
    thisView.accessibilityFrame = CGRectMake(250.0, 0.0, 200.0, 100.0);
    current = thisView;
    [self.view addSubview:current];
}

Answer 1

You are trying to call it as a c function but it is declared as a class method.

In Objective C you need to write

[self setAsPrevious:current];

Answer 2

call [self setAsPrevious:current]; instead of setAsPrevious(current);