XCode/Swift：如何管理两个重叠图像视图的约束答案

【问题标题】：XCode/Swift: how to manage constraints of two overlapping imageviewsXCode/Swift：如何管理两个重叠图像视图的约束
【发布时间】：2016-02-21 20:09:26
【问题描述】：

在我的应用程序中，我想在更大的 UIImageView 上管理一个可拖动的 pin，即 UIImageView。这是我故事板中的截图：

问题是我无法管理约束：我希望 pin 图像只能在下面的大 UIImageView 内拖动。您对如何编写这些约束有任何想法吗？

【问题讨论】：

标签： ios xcode uiimageview constraints draggable

【解决方案1】：

更新：回答

在Main.storyboard 中不需要约束，总体而言，有必要将每个引脚实现为UIImageView 的子类和UIPanGestureRecognizer。这是我将允许引脚移动的尺寸编码到的类：

import UIKit

class PinImageView: UIImageView {

var lastLocation:CGPoint?
var panRecognizer:UIPanGestureRecognizer?

init(imageIcon: UIImage?, location:CGPoint) {
    super.init(image: imageIcon)
    self.lastLocation = location
    self.panRecognizer = UIPanGestureRecognizer(target:self, action:"detectPan:")
    self.center = location
    self.gestureRecognizers = [panRecognizer!]
    self.frame = CGRect(x: location.x, y: location.y, width: 20.0, height: 30.0)
    self.userInteractionEnabled = true
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

func detectPan(recognizer:UIPanGestureRecognizer) {
    let translation  = recognizer.translationInView(self.superview!)
    let newLocation = CGPointMake(lastLocation!.x + translation.x, lastLocation!.y + translation.y)

    if ((newLocation.x >= 26 && newLocation.x <= 292) && (newLocation.y >= 71 && newLocation.y <= 461)){
        self.center = CGPointMake(newLocation.x, newLocation.y)
    }
}

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    // Promote the touched view
    self.superview?.bringSubviewToFront(self)

    // Remember original location
    lastLocation = self.center
}

}

【讨论】：