如果标题有点含糊,请见谅。我仍在学习 swift 和 segues,我有 3 个 View Controller ,分别称为 EarthViewController
、MoonViewController
和 JupiterViewController
。
这些是有效的 segues:
EarthViewController -> MoonViewController
MoonViewController -> JupiterViewController
JupiterViewController -> MoonViewController,
and even JupiterViewController -> EarthViewController,
但是 MoonViewController -> EarthViewController
的 unwind segue 不断抛出一个 Thread 1: Signal SIGABRT
错误,我已经评论了 //ERROR HERE
当试图回到地球 View 时。这是到目前为止的布局和代码:
地球 View Controller (ViewController)
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let des = segue.destination as! MoonViewController
if (segue.identifier == "toMoonView")
{
print("Went to the moon")
}
}
@IBAction func backFromMoon(segue: UIStoryboardSegue){
if let scVC = segue.source as? MoonViewController
{
print ("Back from the Moon to Earth")
}
}
@IBAction func backFromJupiterToEarth(segue: UIStoryboardSegue){
if let scVC = segue.source as? JupiterViewController
{
print ("Back from Jupiter to Earth")
}
}
}
月亮 View Controller
import UIKit
class MoonViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
//------------------------------------------------------------------------
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let des = segue.destination as! JupiterViewController //<- ERROR HERE
if (segue.identifier == "toJupiterView")
{
print("Went to Jupiter")
}
}
//-----------------------------------------------------------------------
@IBAction func backFromJupiter(segue: UIStoryboardSegue){
if let scVC = segue.source as? JupiterViewController
{
print ("Back from Jupiter to the Moon")
}
}
}
JupiterViewController(还没有添加)
import UIKit
class JupiterViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
}
非常感谢任何帮助!谢谢!
最佳答案
MoonViewController
中的这个函数:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
let des = segue.destination as! JupiterViewController //<- ERROR HERE
if (segue.identifier == "toJupiterView")
{
print("Went to Jupiter")
}
}
被调用用于常规转场和展开转场。当您转到 JupiterViewController
时,segue.destination
确实是 JupiterViewController
类型。但是当您展开到 ViewController
时,segue.destination
是 ViewController
类型。
在第二种情况下,强制将 转换为! JupiterViewController
崩溃,因为类型错误。
解决这个问题的一种方法是在确定目标后将 des
的声明移动到 if
中:
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
if segue.identifier == "toJupiterView"
{
let des = segue.destination as! JupiterViewController
print("Went to Jupiter")
}
}
关于ios - 如何让 unwind segue 在同一 View Controller 中与常规 segue 一起工作?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58151082/