在 XML 中找到但在代码中没有找到的 Segue

Question

您好，我有一个关于 segue 的问题，我在这里查看了很多帖子，并且很确定我已经正确设置了 segue。这是我的故事板 XML，有两个场景，SplashScreen 和 ViewController。从 XML 中可以看出，Splash Screen 有一个名为“startSegue”的 segue：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="6751" systemVersion="14C109" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" initialViewController="BYZ-38-t0r">
    <dependencies>
        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="6736"/>
    </dependencies>
    <scenes>
        <!--Splash Screen-->
        <scene sceneID="tne-QT-ifu">
            <objects>
                <viewController autoresizesArchivedViewToFullSize="NO" automaticallyAdjustsScrollViewInsets="NO" modalTransitionStyle="crossDissolve" id="BYZ-38-t0r" customClass="SplashScreen" sceneMemberID="viewController">
                    <layoutGuides>
                        <viewControllerLayoutGuide type="top" id="YHw-QP-f7w"/>
                        <viewControllerLayoutGuide type="bottom" id="2PH-gO-d5q"/>
                    </layoutGuides>
                    <view key="view" contentMode="scaleToFill" id="CXr-Vc-KGH">
                        <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                        <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                        <color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
                    </view>
                    <extendedEdge key="edgesForExtendedLayout"/>
                    <connections>
                        <segue destination="dqe-cT-PeC" kind="push" identifier="startSegue" id="bcv-Eq-8U6"/>
                    </connections>
                </viewController>
                <placeholder placeholderIdentifier="IBFirstResponder" id="dkx-z0-nzr" sceneMemberID="firstResponder"/>
            </objects>
            <point key="canvasLocation" x="306" y="314"/>
        </scene>
        <!--View Controller-->
        <scene sceneID="Pnt-X0-2I5">
            <objects>
                <viewController id="dqe-cT-PeC" sceneMemberID="viewController">
                    <layoutGuides>
                        <viewControllerLayoutGuide type="top" id="w8K-7E-bqp"/>
                        <viewControllerLayoutGuide type="bottom" id="Nj4-1u-ozE"/>
                    </layoutGuides>
                    <view key="view" contentMode="scaleToFill" id="r7Q-nY-3Gv">
                        <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                        <subviews>
                            <view contentMode="scaleToFill" fixedFrame="YES" translatesAutoresizingMaskIntoConstraints="NO" id="yAf-Ru-F3U" customClass="PreviewView">
                                <rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
                                <color key="backgroundColor" white="0.0" alpha="1" colorSpace="calibratedWhite"/>
                            </view>
                        </subviews>
                        <color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
                    </view>
                    <navigationItem key="navigationItem" id="F3Y-vZ-LGa"/>
                </viewController>
                <placeholder placeholderIdentifier="IBFirstResponder" id="n7E-NZ-nYo" userLabel="First Responder" sceneMemberID="firstResponder"/>
            </objects>
            <point key="canvasLocation" x="1021" y="314"/>
        </scene>
    </scenes>
</document>

但是当我调用代码执行 segue 时，它​​出错并说'Receiver () has no segue with identifier 'startSegue''

[self performSegueWithIdentifier: @"startSegue" sender: self];

使用 try-catch 对检查，它与 navigationController 问题无关。

顺便说一句，我在 AppDelegate.m 中使用以下代码设置了 SplashScreen

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    self.viewController = [[SplashScreen alloc] initWithNibName:@"SplashScreen" bundle:nil];

    self.window.rootViewController = self.viewController;
    [self.window makeKeyAndVisible];
    return YES;
}

任何提示将不胜感激！

Answer 1

自从引入 Storyboard 以来，您无需手动创建您的第一个视图控制器。您所要做的就是在项目属性中指定它：

在您的 AppDelegate 中，您现在可以删除您添加的所有初始化代码：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    // The root view controller is already set. 
    return YES;
}

那么您的代码中发生了什么？以下代码行创建了一个没有任何视图的新 SplashScreen 控制器：

[[SplashScreen alloc] initWithNibName:@"SplashScreen" bundle:nil];

由于 SplashScreen 是 Storyboard 文件而非 Nib/Xib 文件，因此未加载并返回 nil 视图。搜索指定的segue时，由于Storyboard没有正确加载，没有找到。