Availability
Technology
func validateValue(_ ioValue: AutoreleasingUnsafeMutablePointer <AnyObject?>,
forKey inKey: String) throws
ioValueA pointer to a new value for the property identified by in. This method may modify or replace the value in order to make it valid.
inKeyThe name of one of the receiver's properties. The key must specify an attribute or a to-one relationship.
A Boolean set to true if the value pointed at by io is valid for the property identified by in, or if the method is able to modify the value at io to make it valid; otherwise false.
The default implementation of this function searches the class of the receiver for a property specific validation function with a particular signature, allowing that function to determine the outcome of the validation. For it to be found, the property specific validation function must be exposed to Objective-C, must be named according to the pattern validate<In, must take a single, optional Any pointer argument, and must throw. For example, for a property named some, the validation function is:
@objc func validateSomeString(_ ioValue: AutoreleasingUnsafeMutablePointer<AnyObject?>) throws {
// Test, and possibly replace the value here; or throw an error
}If you define such a function, the default implementation of validate calls it when asked to validate the corresponding property, allowing your function to either alter the input value or throw an error.
If no such function exists for a particular property, validatereturns without taking any other action. In other words, by default, the general validation call succeeds if you don't explicitly provide a validation function for the given property.
See Adding Validation in Key-Value Coding Programming Guide for more information.
func validateValue (AutoreleasingUnsafeMutablePointer<AnyObject?>, forKeyPath : String)