如果您正在使用自动布局,您不应该仅仅通过改变视图的中心来移动视图。任何导致自动布局运行会将您的视图移回到原来的位置。
这是一个名为的新类的实现DraggableView
与自动布局提供可以拖动的视图。它在代码中为视图的宽度、高度、X 位置和 Y 位置创建约束。它使用自己的UIPanGestureRecognizer
允许拖动视图。
DraggableView.swift可以放入任何需要可拖动视图的项目中。看一眼ViewController.swift下面看看它是多么容易使用。
DraggableView.swift
import UIKit
class DraggableView: UIView {
let superView: UIView!
let xPosConstraint: NSLayoutConstraint!
let yPosConstraint: NSLayoutConstraint!
var constraints: [NSLayoutConstraint] {
get {
return [xPosConstraint, yPosConstraint]
}
}
init(width: CGFloat, height: CGFloat, x: CGFloat, y: CGFloat, color: UIColor, superView: UIView) {
super.init()
self.superView = superView
self.backgroundColor = color
self.setTranslatesAutoresizingMaskIntoConstraints(false)
let panGestureRecognizer = UIPanGestureRecognizer()
panGestureRecognizer.addTarget(self, action: "draggedView:")
self.addGestureRecognizer(panGestureRecognizer)
let widthConstraint = NSLayoutConstraint(item: self, attribute: .Width, relatedBy: .Equal,
toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: width)
self.addConstraint(widthConstraint)
let heightConstraint = NSLayoutConstraint(item: self, attribute: .Height, relatedBy: .Equal,
toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: height)
self.addConstraint(heightConstraint)
xPosConstraint = NSLayoutConstraint(item: self, attribute: .CenterX, relatedBy: .Equal,
toItem: superView, attribute: .Leading, multiplier: 1.0, constant: x)
yPosConstraint = NSLayoutConstraint(item: self, attribute: .CenterY, relatedBy: .Equal,
toItem: superView, attribute: .Top, multiplier: 1.0, constant: y)
}
override init(frame: CGRect) {
super.init(frame: frame)
}
required init(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func moveByDeltaX(deltaX: CGFloat, deltaY: CGFloat) {
xPosConstraint.constant += deltaX
yPosConstraint.constant += deltaY
}
func draggedView(sender:UIPanGestureRecognizer){
if let dragView = sender.view as? DraggableView {
superView.bringSubviewToFront(dragView)
var translation = sender.translationInView(superView)
sender.setTranslation(CGPointZero, inView: superView)
dragView.moveByDeltaX(translation.x, deltaY: translation.y)
}
}
}
ViewController.swift
import UIKit
class ViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let dragView1 = DraggableView(width: 75, height: 75, x: 50, y: 50,
color: UIColor.redColor(), superView: self.view)
self.view.addSubview(dragView1)
self.view.addConstraints(dragView1.constraints)
let dragView2 = DraggableView(width: 100, height: 100, x: 150, y: 50,
color: UIColor.blueColor(), superView: self.view)
self.view.addSubview(dragView2)
self.view.addConstraints(dragView2.constraints)
let dragView3 = DraggableView(width: 125, height: 125, x: 100, y: 175,
color: UIColor.greenColor(), superView: self.view)
self.view.addSubview(dragView3)
self.view.addConstraints(dragView3.constraints)
}
}
UPDATE:
这是一个版本DraggableView.swift支持图像作为子视图。
import UIKit
class DraggableView: UIView {
let superView: UIView!
let xPosConstraint: NSLayoutConstraint!
let yPosConstraint: NSLayoutConstraint!
var constraints: [NSLayoutConstraint] {
get {
return [xPosConstraint, yPosConstraint]
}
}
init(width: CGFloat, height: CGFloat, x: CGFloat, y: CGFloat, color: UIColor, superView: UIView, imageToUse: String? = nil, contentMode: UIViewContentMode = .ScaleAspectFill) {
super.init()
self.superView = superView
self.backgroundColor = color
self.setTranslatesAutoresizingMaskIntoConstraints(false)
let panGestureRecognizer = UIPanGestureRecognizer()
panGestureRecognizer.addTarget(self, action: "draggedView:")
self.addGestureRecognizer(panGestureRecognizer)
let widthConstraint = NSLayoutConstraint(item: self, attribute: .Width, relatedBy: .Equal,
toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: width)
self.addConstraint(widthConstraint)
let heightConstraint = NSLayoutConstraint(item: self, attribute: .Height, relatedBy: .Equal,
toItem: nil, attribute: .NotAnAttribute, multiplier: 1.0, constant: height)
self.addConstraint(heightConstraint)
xPosConstraint = NSLayoutConstraint(item: self, attribute: .CenterX, relatedBy: .Equal,
toItem: superView, attribute: .Leading, multiplier: 1.0, constant: x)
yPosConstraint = NSLayoutConstraint(item: self, attribute: .CenterY, relatedBy: .Equal,
toItem: superView, attribute: .Top, multiplier: 1.0, constant: y)
if imageToUse != nil {
if let image = UIImage(named: imageToUse!) {
let imageView = UIImageView(image: image)
imageView.contentMode = contentMode
imageView.clipsToBounds = true
imageView.setTranslatesAutoresizingMaskIntoConstraints(false)
self.addSubview(imageView)
self.addConstraint(NSLayoutConstraint(item: imageView, attribute: .Left, relatedBy: .Equal, toItem: self, attribute: .Left, multiplier: 1.0, constant: 0))
self.addConstraint(NSLayoutConstraint(item: imageView, attribute: .Top, relatedBy: .Equal, toItem: self, attribute: .Top, multiplier: 1.0, constant: 0))
self.addConstraint(NSLayoutConstraint(item: imageView, attribute: .Right, relatedBy: .Equal, toItem: self, attribute: .Right, multiplier: 1.0, constant: 0))
self.addConstraint(NSLayoutConstraint(item: imageView, attribute: .Bottom, relatedBy: .Equal, toItem: self, attribute: .Bottom, multiplier: 1.0, constant: 0))
}
}
}
override init(frame: CGRect) {
super.init(frame: frame)
}
required init(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
func moveByDeltaX(deltaX: CGFloat, deltaY: CGFloat) {
xPosConstraint.constant += deltaX
yPosConstraint.constant += deltaY
}
func draggedView(sender:UIPanGestureRecognizer){
if let dragView = sender.view as? DraggableView {
superView.bringSubviewToFront(dragView)
var translation = sender.translationInView(superView)
sender.setTranslation(CGPointZero, inView: superView)
dragView.moveByDeltaX(translation.x, deltaY: translation.y)
}
}
}