Just drag the file in Classes
into your project.
You can just use it as UITextField or change the class name as LineField in the storyboard or xib file.
Code
LineField *textfield = [[LineField alloc] initWithFrame:frame];
// Set properties like bottom line color, float label color etc.
[self.view addSubview:textfield];
let field = LineField()
// ...
self.view.addSubview(field)
XIB/Storyboard
Select your textfield control, go to the inspector
=>Custom Class
=>Class
, Change it as LineField
. OK, It's done.