我正在制作一条消息，当tableView为空时显示该消息，并且我在子视图中添加了一个标签，并且它似乎是像素化的。但是当我在tableView中添加一些东西并将其删除时，显示的消息（UILabel）就完全没问题了。无法弄清楚原因。
在我的var b= JSON.stringify(JSON.parse(a));中添加标签解决了它，但我想添加两个标签，因此我在var b = [].concat(a);中添加一个标签，使其像素化。
这是我的代码：
self.tableView.backgroundView = emptyLabel答案 0 :(得分：1)
class Animation {}
// an analogue of the Animation.AnimationListener class
interface AnimationListener {
void onAnimationStart(Animation animation);
void onAnimationEnd(Animation animation);
}
class AnimationListenerBuilder {
// do nothing by default (avoiding a NPE from the build method)
private Consumer<Animation> onAnimationStartCallback = animation -> {};
private Consumer<Animation> onAnimationEndCallback = animation -> {};
public AnimationListenerBuilder setOnAnimationStartCallback(Consumer<Animation> supplier) {
onAnimationStartCallback = supplier;
return this;
}
public AnimationListenerBuilder setOnAnimationEndCallback(Consumer<Animation> supplier) {
onAnimationEndCallback = supplier;
return this;
}
private AnimationListener build() {
return new AnimationListener() {
@Override
public void onAnimationStart(Animation animation) {
onAnimationStartCallback.accept(animation);
}
@Override
public void onAnimationEnd(Animation animation) {
onAnimationEndCallback.accept(animation);
}
};
}
public static void main(String[] args) {
AnimationListenerBuilder builder = new AnimationListenerBuilder();
AnimationListener listener = builder
.setOnAnimationEndCallback(animation -> {})
.setOnAnimationEndCallback(animation -> {})
.build();
}
}
，因此没有好的地方添加子视图，因为每次调用此函数时，另一个UILabel的实例都会添加到视图层次结构中。
删除numberOfRowsInSection中的添加标签。添加类变量：
numberOfRowsInSection然后添加函数
var emptyLabel: UILabel!
var emptyLabel2: UILabel!
var emptyImage: UIImageView!
在 func createEmptyLabels() {
emptyLabel=UILabel(frame: CGRect(x: 0,y: 0, width: self.view.bounds.width, height: self.view.bounds.height))
emptyLabel2=UILabel(frame: CGRect(x: 0.0,y: 20.0, width: self.view.bounds.width, height: self.view.bounds.height))
self.view.addSubview(emptyLabel2)
self.view.addSubview(emptyLabel)
emptyImage = UIImageView(image: UIImage(named: "Quote Right Filled-100 (3)"))
emptyImage.translatesAutoresizingMaskIntoConstraints = false
self.view.addSubview(emptyImage)
emptyImage.alpha=0.1
NSLayoutConstraint.activate([
emptyImage.centerXAnchor.constraint(equalTo: self.view.centerXAnchor),
emptyImage.centerYAnchor.constraint(equalTo: self.view.centerYAnchor),
emptyImage.heightAnchor.constraint(equalToConstant: 90),
emptyImage.widthAnchor.constraint(equalToConstant: 90)
])
emptyLabel.text = "no present reminders"
emptyLabel.textColor=UIColor.darkGray
emptyLabel.font=UIFont(name: "HelveticaNeue-Light", size: 18)
emptyLabel.textAlignment = NSTextAlignment.center
emptyLabel2.text = "you add by going back to the homescreen"
emptyLabel2.textColor=UIColor.gray
emptyLabel2.font=UIFont(name: "HelveticaNeue-Light", size: 11)
emptyLabel2.textAlignment = NSTextAlignment.center
emptyLabel.isHidden = true
emptyLabel2.isHidden = true
emptyImage.isHidden = true
}
和viewDidLoad：
numberOfRowsInSection答案 1 :(得分：1)
您正在numberOfRowsInSection添加标签。问题是这种方法被多次调用。所以你要添加许多标签副本，堆叠在一起，这使得标签看起来很有趣。