问题
Swift function defined in MySwift.swift File:
func SomeSwift()
{
}
SomeSwift() is not defined in any Swift class, it is just a pure function.
After CMD + B to build the project, open Project-Swift.h, the SomeSwift() isn't show in there.
Does the function in Swift have to be defined in some Swift class? and with @objc marked?
like the following:
@objc class SomeSwift: NSObject {
func SomeSwift()
{
}
}
回答1:
Referring to Apple Documentation about Using Swift from Objective-C:
A Swift class must be a descendant of an Objective-C class to be accessible and usable in Objective-C
Means that your class should be @objc class SomeSwift: NSObject (You're right!), but you CANNOT access the whole thing in Swift file:
When you create a Swift class that descends from an Objective-C class, the class and its members—properties, methods, subscripts, and initializers—that are compatible with Objective-C are automatically available from Objective-C. This excludes Swift-only features, such as those listed here:
Generics
Tuples
Enumerations defined in Swift without Int raw value type
Structures defined in Swift
Top-level functions defined in Swift
Global variables defined in Swift
Typealiases defined in Swift
Swift-style variadics
Nested types
Curried functions
Reference.
So, you cannot use the SomeSwift top-level function.
Even if you tried to add @objc before its declaration, the compiler will tell that:
@objc can only used when with memebers of classes, @objc protocols, and concrete extensions of classes.
with a suggestion to remove @objc.
来源：https://stackoverflow.com/questions/40904250/objective-c-call-swift-function