I would say that new apps are being written in Swift, while the old ones will stay with Obj-C. It's too complex to mix Obj-c and Swift, so why go through the trouble?
extension MyViewController {
func myFirstSwiftFunc() -> Bool {
return true
}
} NSString *s = @"Swift is the future";
UIViewController *vc = [[UIViewController alloc] init];
NSArray *names = @[@"John", @"Paul", @"George", @"Ringo"];
let s = "Swift is the future"
let vc = UIViewController()
let names = ["John", "Paul", "George", "Ringo"] let s = "Swift is the future"
let s:String = "Swift is the future"
let s: String = "Swift is the future"