iOS Autolayout 视图高度基于较大的子视图高度

Question

所以我在界面生成器中有一个视图，我希望它的高度基于其中两个子视图中较大的（高度）。但是，只有在加载视图并通过 viewDidLoad 填充内容时才能确定。

所以现在我有了基于灰色文本（“S”）的视图底部布局。在应用程序中的大多数情况下，灰色文本将足够长以换行多行，然后视图高度就可以了。但是，在这种情况下，图像的高度大于文本。界面生成器中是否有任何方法可以将自动布局约束设置为相对于两者中的较大者（实际上，更准确地说，相对于具有最大 maxY 帧位置的元素）？

Answer 1

试试这个：

TestView.xib：

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<document type="com.apple.InterfaceBuilder3.CocoaTouch.XIB" version="3.0" toolsVersion="7706" systemVersion="14D136" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES">
    <dependencies>
        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="7703"/>
    </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="320" height="320"/>
            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
            <subviews>
                <view contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" id="Pbb-AR-WNn">
                    <rect key="frame" x="20" y="87" width="280" height="147"/>
                    <subviews>
                        <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="1000" verticalHuggingPriority="1000" horizontalCompressionResistancePriority="1000" verticalCompressionResistancePriority="1000" image="dragon" translatesAutoresizingMaskIntoConstraints="NO" id="D5g-gu-1ev">
                            <rect key="frame" x="16" y="16" width="64" height="64"/>
                        </imageView>
                        <label opaque="NO" userInteractionEnabled="NO" contentMode="left" verticalHuggingPriority="1000" verticalCompressionResistancePriority="1000" lineBreakMode="tailTruncation" numberOfLines="0" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="5iM-Zb-gNn">
                            <rect key="frame" x="88" y="16" width="176" height="115"/>
                            <string key="text">So I have a view in interface builder and I want its height to be based on the larger (height-wise) of the two subviews inside of it.</string>
                            <fontDescription key="fontDescription" type="system" pointSize="16"/>
                            <color key="textColor" cocoaTouchSystemColor="darkTextColor"/>
                            <nil key="highlightedColor"/>
                        </label>
                    </subviews>
                    <color key="backgroundColor" white="0.90000000000000002" alpha="1" colorSpace="calibratedWhite"/>
                    <constraints>
                        <constraint firstAttribute="width" constant="280" id="2xn-1g-Vuq"/>
                        <constraint firstAttribute="bottom" secondItem="D5g-gu-1ev" secondAttribute="bottom" priority="750" constant="16" id="6rO-0a-xvp"/>
                        <constraint firstAttribute="bottom" secondItem="5iM-Zb-gNn" secondAttribute="bottom" priority="750" constant="16" id="B4u-tf-NJf"/>
                        <constraint firstItem="D5g-gu-1ev" firstAttribute="leading" secondItem="Pbb-AR-WNn" secondAttribute="leading" constant="16" id="GZ7-e9-kF0"/>
                        <constraint firstItem="D5g-gu-1ev" firstAttribute="top" secondItem="Pbb-AR-WNn" secondAttribute="top" constant="16" id="K8m-xD-EsT"/>
                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="D5g-gu-1ev" secondAttribute="bottom" constant="16" id="KEK-Q2-z4j"/>
                        <constraint firstItem="5iM-Zb-gNn" firstAttribute="leading" secondItem="D5g-gu-1ev" secondAttribute="trailing" constant="8" id="QLz-Q2-13S"/>
                        <constraint firstItem="5iM-Zb-gNn" firstAttribute="top" secondItem="Pbb-AR-WNn" secondAttribute="top" constant="16" id="bpN-WA-APq"/>
                        <constraint firstAttribute="bottom" relation="greaterThanOrEqual" secondItem="5iM-Zb-gNn" secondAttribute="bottom" constant="16" id="dbe-Qg-fJU"/>
                        <constraint firstAttribute="trailing" secondItem="5iM-Zb-gNn" secondAttribute="trailing" constant="16" id="yIE-Eq-dw0"/>
                    </constraints>
                </view>
            </subviews>
            <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
            <constraints>
                <constraint firstAttribute="centerY" secondItem="Pbb-AR-WNn" secondAttribute="centerY" id="Ts3-XA-WC0"/>
                <constraint firstAttribute="centerX" secondItem="Pbb-AR-WNn" secondAttribute="centerX" id="uS3-QD-gfi"/>
            </constraints>
            <freeformSimulatedSizeMetrics key="simulatedDestinationMetrics"/>
            <point key="canvasLocation" x="365" y="328"/>
        </view>
    </objects>
    <resources>
        <image name="dragon" width="64" height="64"/>
    </resources>
</document>

约束的构造如下：

H:[panel(280)]
H:|-16-[imageView]-8-[labelView]-16-|
V:|-16-[imageView]-(16@750,>=16)-|
V:|-16-[labelView]-(16@750,>=16)-|

和

imageView.contentHuggingPriorityForAxis(.Vertical) == 1000
imageView.contentCompressionResistancePriorityForAxis(.Vertical) == 1000

labelView.contentHuggingPriorityForAxis(.Vertical) == 1000
labelView.contentCompressionResistancePriorityForAxis(.Vertical) == 1000

Answer 2

Rintaro 的回答非常详细且很有帮助，但它并不完全符合我的要求。它可以将视图保持在某个最小高度，但它也会在静态高度处切断标签。我最终做的只是将两个 >= 底部空间用于容器约束并省略两个 = 。这效果很好。