CodeStructure1.swift

// MARK: {Extension_Name}
extension {Class_Name} {
    fileprivate func {Func_Name}() {
       // It may be reachable from other extensions 
       // This function may use other fileprivate functions from other extensions
    }
     
    private func {Private_Func}()->{Returned_Value} {
       // Do not use any function , but it may use a class variable inside it 
       // Oftenly returns a value
    }
}

// MARK: Public Functions
extension {Class_Name} {
    func {Func_Name}() {
       // Callable function from other classes
       // This function should be as short as possible. 
       // Oftenly in this function it calls other fileprivate function in this class
    }
}