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使用Xamarin.ios将布局约束常量从一个值动画化为另一个值

xamarin-studio uiviewanimation xamarin xamarin.ios ios

Dave Haigh · 技术社区 · 11 年前

我正在使用Xamarin工作室,并使用Xamarin.iOS开发iPad应用程序。

我正在针对c#文件中的布局约束出口设置一个常数值。

我现在有什么(没有动画)

_myRightSpaceConstraint.Constant = 50;

我想要什么

为该常量设置动画,使其从以下位置开始:

_myRightSpaceConstraint.Constant = 300;

到

_myRightSpaceConstraint.Constant=50;

或 ,与上面类似,但没有指定起始常数是多少(300),相反,我只取xib文件中设置的值,并将其设置为50。

在Xamarin中可以做到这一点吗?如果可以,有什么代码示例可以帮助我吗?

我试过的都不起作用

UIView.BeginAnimations ("slideAnimation");
float _pt;
_pt = _myRightSpaceConstraint.Constant;

UIView.SetAnimationDuration (5);
UIView.SetAnimationCurve (UIViewAnimationCurve.EaseInOut);

UIView.SetAnimationDelegate (this);
UIView.SetAnimationDidStopSelector (
    new Selector ("slideAnimationFinished:"));

_myRightSpaceConstraint.Constant = 50;
UIView.CommitAnimations ();

这实际上成功地将常数设置为50,但没有动画。

编辑/更新:

我通过以下方式实现了我想要的目标:

_myRightSpaceConstraint.Constant = 150;
_myViewWithTheConstraint.SetNeedsUpdateConstraints ();

UIView.BeginAnimations ("slideAnimation");

UIView.SetAnimationDuration (1);
UIView.SetAnimationCurve (UIViewAnimationCurve.EaseInOut);

UIView.SetAnimationDelegate (this);
UIView.SetAnimationDidStopSelector (
    new Selector ("slideAnimationFinished:"));

_myViewWithTheConstraint.LayoutIfNeeded ();

UIView.CommitAnimations ();

以下几行是关键:

_myViewWithTheConstraint.LayoutIfNeeded ();

2 回复 | 直到 11 年前

Larry OBrien 11 年前

呼叫 LayoutIfNeeded() 在受约束视图上,作为 animations 的行动 UIView.Animate :

    NSLayoutConstraint[] dynConstraints;
    UIView redView;
    UIView greenView;

    public ContentView()
    {
        BackgroundColor = UIColor.Blue;

        redView = new UIView() {
            BackgroundColor = UIColor.Red,
            TranslatesAutoresizingMaskIntoConstraints = false
        };
        AddSubview(redView);

        greenView = new UIView(){
            BackgroundColor = UIColor.Green,
            TranslatesAutoresizingMaskIntoConstraints = false
        };
        AddSubview(greenView);

        var viewsDictionary = new NSMutableDictionary();
        viewsDictionary["red"] = redView;
        viewsDictionary["green"] = greenView;

        dynConstraints= NSLayoutConstraint.FromVisualFormat("V:|-[red]-100-[green(==red)]-|", 0, new NSDictionary(), viewsDictionary);
        AddConstraints(dynConstraints);
        AddConstraints(NSLayoutConstraint.FromVisualFormat("H:|-[red]-|", 0, new NSDictionary(), viewsDictionary));
        AddConstraints(NSLayoutConstraint.FromVisualFormat("H:|-[green(==red)]", 0, new NSDictionary(), viewsDictionary));

        this.UserInteractionEnabled = true;
    }

    public override void TouchesBegan(NSSet touches, UIEvent evt)
    {
        foreach(var constraint in dynConstraints)
        {
            constraint.Constant = 50;
        }
        UIView.Animate(0.5, () => {
            redView.LayoutIfNeeded();
            greenView.LayoutIfNeeded();
        });
    }

-5

Dave Haigh 11 年前

我通过以下方式实现了我想要的目标:

_myRightSpaceConstraint.Constant = 150;
_myViewWithTheConstraint.SetNeedsUpdateConstraints ();

UIView.BeginAnimations ("slideAnimation");

UIView.SetAnimationDuration (1);
UIView.SetAnimationCurve (UIViewAnimationCurve.EaseInOut);

UIView.SetAnimationDelegate (this);
UIView.SetAnimationDidStopSelector (
    new Selector ("slideAnimationFinished:"));

_myViewWithTheConstraint.LayoutIfNeeded ();

UIView.CommitAnimations ();

以下几行是关键:

_myViewWithTheConstraint.LayoutIfNeeded ();