如果在第一次加载应用程序时尝试执行segue, 我可以在调试器中看到我的打印消息,但Perform Segue不起作用。我没有得到任何错误。 有人可以告诉我什么是错的?在ViewDidLoad中执行Segue
import UIKit
import LocalAuthentication
let isFirstLaunch = UserDefaults.isFirstLaunch()
extension UserDefaults {
// check for is first launch - only true on first invocation after app install, false on all further invocations
// Note: Store this value in AppDelegate if you have multiple places where you are checking for this flag
static func isFirstLaunch() -> Bool {
let hasBeenLaunchedBeforeFlag = "hasBeenLaunchedBeforeFlag"
let isFirstLaunch = !UserDefaults.standard.bool(forKey: hasBeenLaunchedBeforeFlag)
if (isFirstLaunch) {
UserDefaults.standard.set(true, forKey: hasBeenLaunchedBeforeFlag)
UserDefaults.standard.synchronize()
}
return isFirstLaunch
}
}
class loginVC: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
if isFirstLaunch == false {
performSegue(withIdentifier: "setPassword", sender: self)
print("testFalse") }
else {
performSegue(withIdentifier: "setPassword", sender: self)
print("testTrue")}
// Do any additional setup after loading the view, typically from a nib.
}
什么打印在日志中? – Vyacheslav
'testTrue'为第一次启动,'testFalse'为其他? – Vyacheslav
正确。日志中的第一行是testFalse –