iOS 启动故事板中的许多 id 仅显示一个简单的居中图像的目的是什么？

Question

I have this code for an iOS launch storyboard:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="15505" 
          targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" launchScreen="YES" 
          useTraitCollections="YES" colorMatched="YES" initialViewController="01J-lp-oVM">
    <device id="retina5_5" orientation="portrait" appearance="light"/>
    <dependencies>
        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="15509"/>
        <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
    </dependencies>
    <scenes>
        <!--View Controller-->
        <scene sceneID="EHf-IW-A2E">
            <objects>
                <viewController id="01J-lp-oVM" sceneMemberID="viewController">
                    <layoutGuides>
                        <viewControllerLayoutGuide type="top" id="Llm-lL-Icb"/>
                        <viewControllerLayoutGuide type="bottom" id="xb3-aO-Qok"/>
                    </layoutGuides>
                    <view key="view" contentMode="scaleToFill" id="Ze5-6b-2t3">
                        <rect key="frame" x="0.0" y="0.0" width="414" height="736"/>
                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                        <subviews>
                            <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" image="LaunchIcon" translatesAutoresizingMaskIntoConstraints="NO" id="1864">
                                <rect key="frame" x="131" y="292" width="152" height="152"/>
                                <constraints>
                                    <constraint firstAttribute="width" constant="152" id="2074"/>
                                    <constraint firstAttribute="height" constant="152" id="2075"/>
                                </constraints>
                            </imageView>
                        </subviews>
                        <color key="backgroundColor" systemColor="systemBackgroundColor" cocoaTouchSystemColor="whiteColor"/>
                        <constraints>
                            <constraint firstItem="1864" firstAttribute="centerX" secondItem="Ze5-6b-2t3" secondAttribute="centerX" id="2284"/>
                            <constraint firstAttribute="centerY" secondItem="1864" secondAttribute="centerY" id="2285"/>
                        </constraints>
                    </view>
                </viewController>
                <placeholder placeholderIdentifier="IBFirstResponder" id="iYj-Kq-Ea1" userLabel="First Responder" sceneMemberID="firstResponder"/>
            </objects>
            <point key="canvasLocation" x="53" y="375"/>
        </scene>
    </scenes>
</document>

The code seems bloated, filled with IDs and possibly other things I do not need as all it does is display an image in the center.

Can someone give me some suggestions on how I can clean up this code and what I could remove.

Answer 1

The Storyboard format is a human-readable format ( XML ) but it's not open. Unlike XAML , where you can define UI layout without having a designer, Storyboards have to be created with the Storyboard designer (shipped with Xcode ). I wouldn't recommend editing the Storyboard file manually in a text/xml editor because they will be overridden by the Storyboard designer once you open it.

All the identifiers you see inside have an internal storyboard format defined by Apple and used by the Storyboard designer to link elements, containers, and constraints.

I agree that Storyboards introduce less flexibility and a lot of challenges in a multi-team-member environment because they are editable in the designer only:

• one person can introduce changes at a time
• conflicts resolution
• change tracking

Thus, from time to time you will see developers switching to code-only approach and define the UI in the source code only ( Objective-C or Swift ) by creating all the controls and layouts programmatically.