swift - UIlabel 动画不适合屏幕

Question

这是一个问答应用程序，在回答问题后，下一个问题会在屏幕上动画显示。问题是，如果下一个问题是一个较长的问题，它就会越过屏幕。我将标签设置为 2 行。

func animateLabelTransitions(){

    // Animate the alpha
    // and the center X constraints
    let screenWidth = view.frame.width
    self.nextQuestionLabelCenterXConstraint.constant = 0
    self.currentQuestionCenterXConstraint.constant += screenWidth
    UIView.animate(withDuration: 0.5,
                          delay: 0,
                        options: [],
                     animations: {
                                self.currentQuestionLabel.alpha = 0
                                self.nextQuestionLabel.alpha = 1

                                self.view.layoutIfNeeded()
                                },
                     completion: { _ in
                                swap(&self.currentQuestionLabel,
                                &self.nextQuestionLabel)
                                    swap(&self.currentQuestionCenterXConstraint,
                                    &self.nextQuestionLabelCenterXConstraint)

                                    self.updateOffScreenLabel()

                                    })
}

Answer 1

您可以尝试将其放入您的layoutSubviews 方法

self.currentQuestionLabel.preferredMaxLayoutWidth = self.view.frame.width