将 Visual Studio 2017 与 Xamarin 结合使用 - iOS 启动屏幕为黑色/空白

Question

I'm stumped. When I created the project, the LaunchScreen.xib was displaying it's default content that you get when you create a iOS project in Visual Studio. No problem. I decided that I would edit the xib, added a label and a image, now it won't display, on launch of the application I get a black screen. So I deleted everything I added to the xib, figured that would at least get me back to the original launch screen. Nope, still loads black. I've searched all over the web and tried every "fix" I could find. Still black. Tried using Storyboard, creating another xib (MyLaunchScreen.xib), still loads black. It seems that as soon as I touched the original xib, it went to hell in a hand basket. If any has any suggestions on how this can be resolved, I would appreciate it. Thanks.

Answer 1

Maybe you made something corrupt with original .xib

Try the following steps:

1. Uninstall your app in the simulator.

2. Delete original .Xib

3. Create a new .Storyboard or .Xib file

4. Select the new file in info.plist

Answer 2

I found a solution that worked for me, first a little background: The only answer I could find on the web that was specific to my issue uses Visual Studio 2015. The answer said to create my own launch screen by right clicking on Resources and adding a "LaunchScreen.xib" to the resources folder, there was no such option in 2017. Apparently Visual Studio has changed a little so that when your right click on the Resources folder and add a new item, it allows you to select a "View" which is a .xib. I did that and got what I was looking for, added the labels and image view I wanted and now all works as I want. I'm pretty sure that the issue was due to the constraints built into the default LaunchScreen.xib, the constraint system used in Xamarin for Visual Studio 2017 confuses the bejesus out of me so the LaunchScreen.xib I created has no constraints. This may bite me later when I attempt to release the app on the Apple Store, but I'll deal with that later. Below is the LaunchScreen.xib, which is nothing more that an XML file, that does not work followed by the one that does not, maybe someone can explain the whole constraint thing to me that makes sense to me. Right now, ugh.

LaunchScreen.xib (excuse the formatting if I don't get it exactly right):

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
    <document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="11762" systemVersion="15G18013" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" launchScreen="YES" useTraitCollections="YES" colorMatched="YES">
        <dependencies>
            <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="11757"/>
            <capability name="Constraints with non-1.0 multipliers" minToolsVersion="5.1"/>
            <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
        </dependencies>
            <objects>
                <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner"/>
                <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
                     <view contentMode="scaleToFill" id="iN0-l3-epB">
                         <rect key="frame" x="0.0" y="0.0" width="480" height="480"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                     <subviews>
                         <label opaque="NO" clipsSubviews="YES" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="  Copyright (c) 2017 C &amp; G Associates, Inc." textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" minimumFontSize="9" translatesAutoresizingMaskIntoConstraints="NO" id="8ie-xW-0ye">
                             <rect key="frame" x="20" y="439" width="440" height="21"/>
                             <fontDescription key="fontDescription" type="system" pointSize="17"/>
                             <color key="textColor" cocoaTouchSystemColor="darkTextColor"/>
                             <nil key="highlightedColor"/>
                        </label>
                        <label opaque="NO" clipsSubviews="YES" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Sample Out" textAlignment="center" lineBreakMode="middleTruncation" baselineAdjustment="alignBaselines" minimumFontSize="18" translatesAutoresizingMaskIntoConstraints="NO" id="kId-c2-rCX" misplaced="YES">
                            <rect key="frame" x="20" y="36" width="440" height="43"/>
                            <fontDescription key="fontDescription" name="TimesNewRomanPS-BoldItalicMT" family="Times New Roman" pointSize="36"/>
                            <color key="textColor" cocoaTouchSystemColor="darkTextColor"/>
                            <nil key="highlightedColor"/>
                       </label>
                   </subviews>
                   <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
                   <constraints>
                       <constraint firstItem="kId-c2-rCX" firstAttribute="centerY" secondItem="iN0-l3-epB" secondAttribute="bottom" multiplier="1/3" constant="1" id="5cJ-9S-tgC"/>
                       <constraint firstAttribute="centerX" secondItem="kId-c2-rCX" secondAttribute="centerX" id="Koa-jz-hwk"/>
                       <constraint firstAttribute="bottom" secondItem="8ie-xW-0ye" secondAttribute="bottom" constant="20" id="Kzo-t9-V3l"/>
                       <constraint firstItem="8ie-xW-0ye" firstAttribute="leading" secondItem="iN0-l3-epB" secondAttribute="leading" constant="20" symbolic="YES" id="MfP-vx-nX0"/>
                       <constraint firstAttribute="centerX" secondItem="8ie-xW-0ye" secondAttribute="centerX" id="ZEH-qu-HZ9"/>
                       <constraint firstItem="kId-c2-rCX" firstAttribute="leading" secondItem="iN0-l3-epB" secondAttribute="leading" constant="20" symbolic="YES" id="fvb-Df-36g"/>
                   </constraints>
                   <nil key="simulatedStatusBarMetrics"/>
                   <freeformSimulatedSizeMetrics key="simulatedDestinationMetrics"/>
                   <point key="canvasLocation" x="548" y="455"/>
                   <accessibility key="accessibilityConfiguration">
                        <bool key="isElement" value="YES"/>
                   </accessibility>
                   <connections>
                       <outlet property="lblCopyRight" destination="8ie-xW-0ye" id="name-outlet-8ie-xW-0ye"/>
                   </connections>
                </view>
            </objects>
            <resources>
                <image name="CarpetSample.png" width="1294" height="861"/>
            </resources>
</document>

MyLaunchScreen.xib (this works):

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
    <document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="11762" systemVersion="15G18013" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" launchScreen="YES">
    <device id="ipad9_7" orientation="portrait">
        <adaptation id="fullscreen"/>
    </device>
    <dependencies>
        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="11757"/>
        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
    </dependencies>
    <objects>
        <placeholder placeholderIdentifier="IBFilesOwner" id="-1" userLabel="File's Owner"/>
        <placeholder placeholderIdentifier="IBFirstResponder" id="-2" customClass="UIResponder"/>
        <view contentMode="scaleToFill" id="1">
            <rect key="frame" x="0.0" y="0.0" width="768" height="1024"/>
            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
            <color key="backgroundColor" red="1" green="1" blue="1" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
            <subviews>
                <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Sample Out" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" id="165" translatesAutoresizingMaskIntoConstraints="NO" fixedFrame="YES">
                    <rect key="frame" x="0.0" y="29" width="768" height="58"/>
                    <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                    <fontDescription key="fontDescription" name="TimesNewRomanPS-BoldItalicMT" family="Times New Roman" pointSize="36"/>
                    <nil key="textColor"/>
                    <nil key="highlightedColor"/>
                </label>
                <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" id="268" translatesAutoresizingMaskIntoConstraints="NO" fixedFrame="YES" text="Copyright (c) 2017 C &amp; G Associates, Inc.">
                    <rect key="frame" x="0.0" y="943" width="768" height="45"/>
                    <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                    <fontDescription key="fontDescription" type="system" pointSize="17"/>
                    <nil key="textColor"/>
                    <nil key="highlightedColor"/>
                </label>
                <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" id="328" translatesAutoresizingMaskIntoConstraints="NO" fixedFrame="YES" image="CarpetSample.png">
                    <rect key="frame" x="43" y="111" width="685" height="806"/>
                    <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                </imageView>
            </subviews>
        </view>
    </objects>
    <resources>
        <image name="CarpetSample.png" width="1294" height="861"/>
    </resources>
</document>

Answer 3

If anybody else coming here follow Cole Xia - MSFT answer above, you probably using background image that fill the screen and it has something wrong with it, to make sure put label on top with bright color if the label appears then keep this mind:

1. To avoid any properties you may have changed before it is better to create a new View .xib
2. when you run it try using different simulator (ie like iphone 6, iphone 7 etc) or uninstall it before to avoid any caching saved in the device.
3. Usually the cause is the constraints that make the image responsive to different screen sizes, if not done properly will make it confuse and show it black, you can design it to one device size then check in design mode for other devices, it should tell you by red dots square calculated position or you will notice it is stretching check this video https://youtu.be/i54LzXWwLuc also in layout check that you have only four constraints if you stretching your bg image in four directions.
4. Check also here how to make image background in splash https://stackoverflow.com/a/47749043/10327213

Answer 4

Some root causes for this could be

• Misconfiguration in info.plist. Since iOS 8, iOS accepts universal launch screen storyboard. The name for launch screen in info.plist should match the actual launch screen name.
• Launch screen Storyboard/XIB file got corrupted. Storyboard and XIB files can get corrupted sometimes. We may be able to figure it out by checking the XML source of the file. In my case, I had copied some view controllers from another storyboard file and deleted some of the existing ones. Each view controller has a unique id in the storyboard. My Storyboard was keeping the id of a deleted View controller as the initialViewController . By changing the value of this property to the id of a valid viewcontroller that existed in storyboard, the issue got fixed for me.