如何以及在何处检测到自定义UIView大小动态更改并相应地调整滚动视图？

Question

iOS 9+, Swift 3.0

There are three classes:

1. CustomTextField . It can have two states: error and normal . This class inherits from UIView. It has a stackView . That stackView has a UITextField and a UILabel that displays an error if needed. The validation and behaviour in case of error is hidden in this class. When there is an error, the stackView get's the UILabel view added and it grows in height.
2. BaseViewController , it has a scrollView. It implements the behaviour of scrolling up a view if a keyboard appears.
3. ImplementationViewController . It inherits from BaseViewController and has a property of type CustomTextField .

When in the ImplementationViewController a user taps on the CustomTextField , a keyboard comes up and the CustomTextField is scrolled up right above the keyboard.

When the keyboard is visible, if user types an erroneous text, then an error slides down from the bottom of the CustomTextField .

How and where to implement the behaviour to move the scroll view up when the CustomTextField shows an error; and move the scroll view down when the error is being hidden?

Answer 1

Create a protocol CustomTextFieldDelegate and inside it add a method call it InformImplemntation and declare delegate variable in CustomTextField class

CustomTextField().delegate = self [ImplementationViewController]

and when there is an error or not call delegate method and from ImplementationViewController as it inherits from BaseViewController manage whether to hide/show keyboard