不使用自动布局时PrepareForSege崩溃
我有两个Xcode项目，第一个叫做blank，新的和使用自动布局（默认）。第二个称为test，并未使用自动布局（而是使用iPhone布局）。
在测试项目中，方法prepareForSegue崩溃：
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender {
if ([[segue identifier] isEqualToString:@"showDetail"]) {
NSIndexPath *indexPath = [self.tableView indexPathForSelectedRow];
NSDate *object = self.objects[indexPath.row];
/*The program crashed here */ DetailViewController *controller = (DetailViewController *)[[segue destinationViewController] topViewController];
[controller setDetailItem:object];
controller.navigationItem.leftBarButtonItem = self.splitViewController.displayModeButtonItem;
controller.navigationItem.leftItemsSupplementBackButton = YES;
}
}
除了故事板的XML文件之外，两个项目之间的代码没有差异。
blank的故事板：
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="9532" systemVersion="15D21" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" initialViewController="H1p-Uh-vWS">
<dependencies>
<deployment identifier="iOS"/>
<plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="9530"/>
</dependencies>
<scenes>
<!--Master-->
<scene sceneID="pY4-Hu-kfo">
<objects>
<navigationController title="Master" id="RMx-3f-FxP" sceneMemberID="viewController">
<navigationBar key="navigationBar" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" id="Pmd-2v-anx">
<autoresizingMask key="autoresizingMask"/>
</navigationBar>
<connections>
<segue destination="7bK-jq-Zjz" kind="relationship" relationship="rootViewController" id="tsl-Nk-0bq"/>
</connections>
</navigationController>
<placeholder placeholderIdentifier="IBFirstResponder" id="8fS-aE-onr" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="-38" y="-630"/>
</scene>
<!--Detail-->
<scene sceneID="yUG-lL-AsK">
<objects>
<viewController title="Detail" id="JEX-9P-axG" customClass="DetailViewController" sceneMemberID="viewController">
<layoutGuides>
<viewControllerLayoutGuide type="top" id="SYR-Wa-9uf"/>
<viewControllerLayoutGuide type="bottom" id="GAO-Cl-Wes"/>
</layoutGuides>
<view key="view" contentMode="scaleToFill" id="svH-Pt-448">
<rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
<autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
<subviews>
<label clipsSubviews="YES" userInteractionEnabled="NO" contentMode="scaleToFill" text="Detail view content goes here" textAlignment="center" lineBreakMode="tailTruncation" minimumFontSize="10" translatesAutoresizingMaskIntoConstraints="NO" id="0XM-y9-sOw">
<rect key="frame" x="20" y="292" width="560" height="17"/>
<color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
<fontDescription key="fontDescription" type="system" size="system"/>
<color key="textColor" red="0.0" green="0.0" blue="0.0" alpha="1" colorSpace="calibratedRGB"/>
<nil key="highlightedColor"/>
</label>
</subviews>
<color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
<constraints>
<constraint firstItem="0XM-y9-sOw" firstAttribute="leading" secondItem="svH-Pt-448" secondAttribute="leading" constant="20" symbolic="YES" id="Tsc-yG-G1q"/>
<constraint firstItem="0XM-y9-sOw" firstAttribute="centerY" secondItem="svH-Pt-448" secondAttribute="centerY" id="jWN-iV-94e"/>
<constraint firstAttribute="trailing" secondItem="0XM-y9-sOw" secondAttribute="trailing" constant="20" symbolic="YES" id="tHV-ZD-HQj"/>
</constraints>
</view>
<toolbarItems/>
<navigationItem key="navigationItem" title="Detail" id="mOI-FS-AaM"/>
<connections>
<outlet property="detailDescriptionLabel" destination="0XM-y9-sOw" id="deQ-Na-JPF"/>
</connections>
</viewController>
<placeholder placeholderIdentifier="IBFirstResponder" id="FJe-Yq-33r" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="709" y="129"/>
</scene>
<!--Split View Controller-->
<scene sceneID="Nki-YV-4Qg">
<objects>
<splitViewController id="H1p-Uh-vWS" sceneMemberID="viewController">
<toolbarItems/>
<connections>
<segue destination="RMx-3f-FxP" kind="relationship" relationship="masterViewController" id="BlO-5A-QYV"/>
<segue destination="vC3-pB-5Vb" kind="relationship" relationship="detailViewController" id="Tll-UG-LXB"/>
</connections>
</splitViewController>
<placeholder placeholderIdentifier="IBFirstResponder" id="cZU-Oi-B1e" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="-856" y="-330"/>
</scene>
<!--Master-->
<scene sceneID="smW-Zh-WAh">
<objects>
<tableViewController title="Master" clearsSelectionOnViewWillAppear="NO" id="7bK-jq-Zjz" customClass="MasterViewController" sceneMemberID="viewController">
<tableView key="view" clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" dataMode="prototypes" style="plain" separatorStyle="default" rowHeight="44" sectionHeaderHeight="22" sectionFooterHeight="22" id="r7i-6Z-zg0">
<rect key="frame" x="0.0" y="0.0" width="600" height="600"/>
<autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
<color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
<prototypes>
<tableViewCell contentMode="scaleToFill" selectionStyle="blue" hidesAccessoryWhenEditing="NO" indentationLevel="1" indentationWidth="0.0" reuseIdentifier="Cell" textLabel="Arm-wq-HPj" style="IBUITableViewCellStyleDefault" id="WCw-Qf-5nD">
<rect key="frame" x="0.0" y="86" width="600" height="44"/>
<autoresizingMask key="autoresizingMask"/>
<tableViewCellContentView key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" tableViewCell="WCw-Qf-5nD" id="37f-cq-3Eg">
<rect key="frame" x="0.0" y="0.0" width="600" height="43.5"/>
<autoresizingMask key="autoresizingMask"/>
<subviews>
<label opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" text="Title" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" id="Arm-wq-HPj">
<rect key="frame" x="15" y="0.0" width="570" height="43.5"/>
<autoresizingMask key="autoresizingMask"/>
<fontDescription key="fontDescription" type="boldSystem" pointSize="20"/>
<color key="textColor" red="0.0" green="0.0" blue="0.0" alpha="1" colorSpace="calibratedRGB"/>
<color key="highlightedColor" red="1" green="1" blue="1" alpha="1" colorSpace="calibratedRGB"/>
</label>
</subviews>
</tableViewCellContentView>
<color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
<connections>
<segue destination="vC3-pB-5Vb" kind="showDetail" identifier="showDetail" id="6S0-TO-JiA"/>
</connections>
</tableViewCell>
</prototypes>
<sections/>
<connections>
<outlet property="dataSource" destination="7bK-jq-Zjz" id="Gho-Na-rnu"/>
<outlet property="delegate" destination="7bK-jq-Zjz" id="RA6-mI-bju"/>
</connections>
</tableView>
<navigationItem key="navigationItem" title="Master" id="Zdf-7t-Un8"/>
</tableViewController>
<placeholder placeholderIdentifier="IBFirstResponder" id="Rux-fX-hf1" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="709" y="-630"/>
</scene>
<!--Navigation Controller-->
<scene sceneID="r7l-gg-dq7">
<objects>
<navigationController id="vC3-pB-5Vb" sceneMemberID="viewController">
<navigationBar key="navigationBar" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" id="DjV-YW-jjY">
<autoresizingMask key="autoresizingMask"/>
</navigationBar>
<connections>
<segue destination="JEX-9P-axG" kind="relationship" relationship="rootViewController" id="GKi-kA-LjT"/>
</connections>
</navigationController>
<placeholder placeholderIdentifier="IBFirstResponder" id="SLD-UC-DBI" userLabel="First Responder" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="-45" y="129"/>
</scene>
</scenes>
<inferredMetricsTieBreakers>
<segue reference="6S0-TO-JiA"/>
</inferredMetricsTieBreakers>
</document>
test的故事板：
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="9532" systemVersion="15D21" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" initialViewController="H1p-Uh-vWS">
<dependencies>
<deployment identifier="iOS"/>
<plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="9530"/>
</dependencies>
<scenes>
<!--Master-->
<scene sceneID="pY4-Hu-kfo">
<objects>
<navigationController title="Master" id="RMx-3f-FxP" sceneMemberID="viewController">
<navigationBar key="navigationBar" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" id="Pmd-2v-anx">
<autoresizingMask key="autoresizingMask"/>
</navigationBar>
<connections>
<segue destination="7bK-jq-Zjz" kind="relationship" relationship="rootViewController" id="tsl-Nk-0bq"/>
</connections>
</navigationController>
<placeholder placeholderIdentifier="IBFirstResponder" id="8fS-aE-onr" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="-20.266666666666666" y="-596.39999999999998"/>
</scene>
<!--Detail-->
<scene sceneID="yUG-lL-AsK">
<objects>
<viewController title="Detail" id="JEX-9P-axG" customClass="DetailViewController" sceneMemberID="viewController">
<view key="view" contentMode="scaleToFill" id="svH-Pt-448">
<rect key="frame" x="0.0" y="0.0" width="320" height="568"/>
<autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
<subviews>
<label clipsSubviews="YES" userInteractionEnabled="NO" contentMode="scaleToFill" text="Detail view content goes here" textAlignment="center" lineBreakMode="tailTruncation" minimumFontSize="10" id="0XM-y9-sOw">
<rect key="frame" x="8" y="262" width="280" height="17"/>
<autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
<color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
<fontDescription key="fontDescription" type="system" size="system"/>
<color key="textColor" red="0.0" green="0.0" blue="0.0" alpha="1" colorSpace="calibratedRGB"/>
<nil key="highlightedColor"/>
</label>
</subviews>
<color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
</view>
<toolbarItems/>
<navigationItem key="navigationItem" title="Detail" id="mOI-FS-AaM"/>
<connections>
<outlet property="detailDescriptionLabel" destination="0XM-y9-sOw" id="deQ-Na-JPF"/>
</connections>
</viewController>
<placeholder placeholderIdentifier="IBFirstResponder" id="FJe-Yq-33r" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="405.86666666666667" y="163.77333333333334"/>
</scene>
<!--Split View Controller-->
<scene sceneID="Nki-YV-4Qg">
<objects>
<splitViewController id="H1p-Uh-vWS" sceneMemberID="viewController">
<toolbarItems/>
<connections>
<segue destination="RMx-3f-FxP" kind="relationship" relationship="masterViewController" id="BlO-5A-QYV"/>
<segue destination="vC3-pB-5Vb" kind="relationship" relationship="detailViewController" id="Tll-UG-LXB"/>
</connections>
</splitViewController>
<placeholder placeholderIdentifier="IBFirstResponder" id="cZU-Oi-B1e" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="-456.5333333333333" y="-312.39999999999998"/>
</scene>
<!--Master-->
<scene sceneID="smW-Zh-WAh">
<objects>
<tableViewController title="Master" clearsSelectionOnViewWillAppear="NO" id="7bK-jq-Zjz" customClass="MasterViewController" sceneMemberID="viewController">
<tableView key="view" clipsSubviews="YES" contentMode="scaleToFill" alwaysBounceVertical="YES" dataMode="prototypes" style="plain" separatorStyle="default" rowHeight="44" sectionHeaderHeight="22" sectionFooterHeight="22" id="r7i-6Z-zg0">
<rect key="frame" x="0.0" y="0.0" width="320" height="568"/>
<autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
<color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
<prototypes>
<tableViewCell contentMode="scaleToFill" selectionStyle="blue" accessoryType="disclosureIndicator" hidesAccessoryWhenEditing="NO" indentationLevel="1" indentationWidth="0.0" reuseIdentifier="Cell" textLabel="Arm-wq-HPj" style="IBUITableViewCellStyleDefault" id="WCw-Qf-5nD">
<rect key="frame" x="0.0" y="86" width="320" height="44"/>
<autoresizingMask key="autoresizingMask"/>
<tableViewCellContentView key="contentView" opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" tableViewCell="WCw-Qf-5nD" id="37f-cq-3Eg">
<rect key="frame" x="0.0" y="0.0" width="287" height="43.5"/>
<autoresizingMask key="autoresizingMask"/>
<subviews>
<label opaque="NO" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="center" text="Title" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" id="Arm-wq-HPj">
<rect key="frame" x="15" y="0.0" width="270" height="43.5"/>
<autoresizingMask key="autoresizingMask"/>
<fontDescription key="fontDescription" type="boldSystem" pointSize="20"/>
<color key="textColor" red="0.0" green="0.0" blue="0.0" alpha="1" colorSpace="calibratedRGB"/>
<color key="highlightedColor" red="1" green="1" blue="1" alpha="1" colorSpace="calibratedRGB"/>
</label>
</subviews>
</tableViewCellContentView>
<color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
<connections>
<segue destination="JEX-9P-axG" kind="push" identifier="showDetail" id="6S0-TO-JiA"/>
</connections>
</tableViewCell>
</prototypes>
<sections/>
<connections>
<outlet property="dataSource" destination="7bK-jq-Zjz" id="Gho-Na-rnu"/>
<outlet property="delegate" destination="7bK-jq-Zjz" id="RA6-mI-bju"/>
</connections>
</tableView>
<navigationItem key="navigationItem" title="Master" id="Zdf-7t-Un8"/>
</tableViewController>
<placeholder placeholderIdentifier="IBFirstResponder" id="Rux-fX-hf1" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="378.13333333333333" y="-596.39999999999998"/>
</scene>
<!--Navigation Controller-->
<scene sceneID="r7l-gg-dq7">
<objects>
<navigationController id="vC3-pB-5Vb" sceneMemberID="viewController">
<navigationBar key="navigationBar" clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" id="DjV-YW-jjY">
<autoresizingMask key="autoresizingMask"/>
</navigationBar>
<connections>
<segue destination="JEX-9P-axG" kind="relationship" relationship="rootViewController" id="GKi-kA-LjT"/>
</connections>
</navigationController>
<placeholder placeholderIdentifier="IBFirstResponder" id="SLD-UC-DBI" userLabel="First Responder" sceneMemberID="firstResponder"/>
</objects>
<point key="canvasLocation" x="-24" y="122.12"/>
</scene>
</scenes>
<inferredMetricsTieBreakers>
<segue reference="6S0-TO-JiA"/>
</inferredMetricsTieBreakers>
</document>
因此，当我启动test时，收到此错误消息：
2016-02-16 15:40:58.960 test[75054:13748065] -[DetailViewController topViewController]: unrecognized selector sent to instance 0x7fbe82c3c480
2016-02-16 15:40:58.964 test[75054:13748065] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[DetailViewController topViewController]: unrecognized selector sent to instance 0x7fbe82c3c480'
*** First throw call stack:
(
0 CoreFoundation 0x000000010ed14e65 __exceptionPreprocess + 165
1 libobjc.A.dylib 0x000000010e78ddeb objc_exception_throw + 48
2 CoreFoundation 0x000000010ed1d48d -[NSObject(NSObject) doesNotRecognizeSelector:] + 205
3 CoreFoundation 0x000000010ec6a90a ___forwarding___ + 970
4 CoreFoundation 0x000000010ec6a4b8 _CF_forwarding_prep_0 + 120
5 test 0x000000010e28c459 -[MasterViewController prepareForSegue:sender:] + 377
6 UIKit 0x000000010f7eaf01 -[UIStoryboardSegueTemplate _performWithDestinationViewController:sender:] + 369
7 UIKit 0x000000010f7ead5f -[UIStoryboardSegueTemplate _perform:] + 82
8 UIKit 0x000000010f7eb023 -[UIStoryboardSegueTemplate perform:] + 156
9 UIKit 0x000000010f204cee -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1775
10 UIKit 0x000000010f204fb3 -[UITableView _userSelectRowAtPendingSelectionIndexPath:] + 388
11 UIKit 0x000000010f0cd4a2 _runAfterCACommitDeferredBlocks + 317
12 UIKit 0x000000010f0e0c01 _cleanUpAfterCAFlushAndRunDeferredBlocks + 95
13 UIKit 0x000000010f0ecaf3 _afterCACommitHandler + 90
14 CoreFoundation 0x000000010ec40367 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 23
15 CoreFoundation 0x000000010ec402d7 __CFRunLoopDoObservers + 391
16 CoreFoundation 0x000000010ec35f2b __CFRunLoopRun + 1147
17 CoreFoundation 0x000000010ec35828 CFRunLoopRunSpecific + 488
18 GraphicsServices 0x00000001124d1ad2 GSEventRunModal + 161
19 UIKit 0x000000010f0c1610 UIApplicationMain + 171
20 test 0x000000010e28cc3f main + 111
21 libdyld.dylib 0x000000011145092d start + 1
22 ??? 0x0000000000000001 0x0 + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb)
几乎所有的程序都是一样的，所以也许我还没有理解视图控制器是如何工作的......我以为我有。你知道它为什么会这样崩溃吗？
3 个答案:
答案 0 :(得分：0)
[segue destinationViewController]属于id类型。此属性包含视图控制器，其内容应显示在segue的末尾。行[[segue destinationViewController] topViewController]（在prepareForSegue :)中崩溃导致destinationViewController没有实现topViewController选择器/属性。 topViewController选择器通常会发送到UINavigationController。所以我猜（没有看到你的其他代码）UINavigationController以某种方式参与你的流程。 Autolayouts与此无关。
只需检查调试目的：
if([segue destinationViewController] isKindOfClass:[UINavigationController class]) {
//Should not crash
}
else {
//Obviously you're doing something wrong
}
答案 1 :(得分：0)
在您的代码行中DetailViewController *controller = (DetailViewController *)[[segue destinationViewController] topViewController];表示目标viewController的消息topViewController不存在。
所以它不是Autolayout
试试这个：DetailViewController *controller = (DetailViewController *)[segue destinationViewController];
如果你想使用topViewController，那么使用self.navigationController topViewController]来获取navigationViewController堆栈中的顶级对象
答案 2 :(得分：0)
由于自动布局但尺寸类不会发生这种情况。 使用Size Classes，您的segue类型为Show Detail，并指向具有DetailViewController作为根视图控制器的UINavigationController。 当您禁用自动布局时，默认情况下禁用大小类，并且您的显示详细信息segue会自动转换为直接指向DetailViewController而不是UINavigationController的Push segue。
所以，
DetailViewController *controller = (DetailViewController *)[[segue destinationViewController] topViewController];
无法工作，因为您现在正在处理DetailViewController的实例，而不是UINavigationController。 topViewController是一条消息，您可以发送给UINavigationController，但不能发送给DetailViewController。
尝试
DetailViewController *controller = (DetailViewController *)[segue destinationViewController];
代替。
请参阅屏幕截图以便更好地理解。
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