坐标更新后图像不刷新

Question

我有一个 UIImage (happyFace)，当用户点击它时我会在屏幕上移动。我还有一个计数器 (tapLabel)，每次点击图像时它都会更新。当我注释掉 tapLabel.text 的更新时，图像在屏幕上移动。当我更新 tapLabel.text 时，图像保持原样，但其 X 和 Y 坐标已更新。我正在使用 AutoLayout 但对 UIImage 没有任何限制。奇怪...

    // Assign the image's new position and update counter label
    happyFace.frame.origin.x = CGFloat(newX)
    happyFace.frame.origin.y = CGFloat(newY)

    tapLabel.text = String(tapCount)

我错过了什么？

Answer 1

我打开了 AutoLayout，所以它总是会把图像重新定位到原来的位置。我需要更新允许 AutoLayout 执行此操作的约束。然后我的图像能够在屏幕上移动。我为我的图像找到了一个新位置（newX，newY）并将它们设置为我的新约束。

// Set up outlets from the image's constraints in the Storyboard
@IBOutlet weak var leadingConstraint: NSLayoutConstraint!
@IBOutlet weak var topConstraint: NSLayoutConstraint!


    // Set a new Leading (X) and Top (Y) constraints for the image
    let newLeadingConstraint = NSLayoutConstraint(item: happyFace, attribute: .Leading, relatedBy: .Equal, toItem: self.view, attribute: .Leading, multiplier: 1.0, constant: newX)
    let newTopConstraint     = NSLayoutConstraint(item: happyFace, attribute: .Top, relatedBy: .Equal, toItem: self.view, attribute: .Top, multiplier: 1.0, constant: newY)

    // Remove the old image constraints and set the new ones (ie move the image)
    self.view.removeConstraint(leadingConstraint)
    self.view.removeConstraint(topConstraint)
    self.view.addConstraint(newLeadingConstraint)
    self.view.addConstraint(newTopConstraint)
    self.view.layoutIfNeeded()                 // Force the layout before drawing
    leadingConstraint = newLeadingConstraint
    topConstraint = newTopConstraint

坐标更新后图像不刷新

Image doesn't refresh after coordinate update

uiimage

ios