我得到了与https://stackoverflow.com/questions/28275004/uidynamicanimator-stop-reacting-to-uigravitybehavior中所述完全相同的问题。我也无法解释得更清楚。
有人知道为什么UIDynamicAnimator会突然停止对附加了UIGravityBehavior的对象/项设置动画吗？
编辑
我正在运行Big Nerd Ranch中的示例
我修改了示例，因此只有两个立方体，以便更容易地再现错误。立方体正在下降，对重力的反应很好，但如果你倾斜手机，使立方体最终在角落里，相互接触，然后它停止任何运动，从而不再对重力行为作出反应。
我也在想，这是否是一个迅速的问题。也许我应该尝试在Obj-C中实现它，看看错误是否仍然存在。
下面是一个例子：
//
// ViewController.swift
// Rock Box
//
// Created by Steve Sparks on 7/11/14.
// Copyright (c) 2014 Big Nerd Ranch. All rights reserved.
//
import UIKit
import CoreMotion
class ViewController: UIViewController {
// Most conservative guess. We'll set them later.
var maxX : CGFloat = 320;
var maxY : CGFloat = 320;
let boxSize : CGFloat = 30.0
var boxes : Array<UIView> = []
// For getting device motion updates
let motionQueue = NSOperationQueue()
let motionManager = CMMotionManager()
override func viewDidLoad() {
super.viewDidLoad()
maxX = super.view.bounds.size.width - boxSize;
maxY = super.view.bounds.size.height - boxSize;
// Do any additional setup after loading the view, typically from a nib.
createAnimatorStuff()
generateBoxes()
}
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
NSLog("Starting gravity")
motionManager.startDeviceMotionUpdatesToQueue(motionQueue, withHandler: gravityUpdated)
}
override func viewDidDisappear(animated: Bool) {
super.viewDidDisappear(animated)
NSLog("Stopping gravity")
motionManager.stopDeviceMotionUpdates()
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
NSLog("Memory warning")
// Dispose of any resources that can be recreated.
}
func randomColor() -> UIColor {
let red = CGFloat(CGFloat(arc4random()%100000)/100000)
let green = CGFloat(CGFloat(arc4random()%100000)/100000)
let blue = CGFloat(CGFloat(arc4random()%100000)/100000)
return UIColor(red: red, green: green, blue: blue, alpha: 0.85);
}
func doesNotCollide(testRect: CGRect) -> Bool {
for box : UIView in boxes {
var viewRect = box.frame;
if(CGRectIntersectsRect(testRect, viewRect)) {
return false
}
}
return true
}
func randomFrame() -> CGRect {
var guess = CGRectMake(9, 9, 9, 9)
do {
let guessX = CGFloat(arc4random()) % maxX
let guessY = CGFloat(arc4random()) % maxY;
guess = CGRectMake(guessX, guessY, boxSize, boxSize);
} while(!doesNotCollide(guess))
return guess
}
func addBox(location: CGRect, color: UIColor) -> UIView {
let newBox = UIButton(frame: location)
newBox.backgroundColor = color
view.addSubview(newBox)
addBoxToBehaviors(newBox)
self.boxes.append(newBox)
newBox.tag = Int(arc4random())
newBox.addTarget(self, action:"tapped:", forControlEvents: .TouchUpInside)
return newBox
}
func tapped(sender: UIButton) {
println("sender.tag: ", Int(sender.tag))
}
func generateBoxes() {
for i in 0..<2 {
var frame = randomFrame()
var color = randomColor()
var newBox = addBox(frame, color: color);
}
}
var animator:UIDynamicAnimator? = nil;
let gravity = UIGravityBehavior()
let collider = UICollisionBehavior()
let itemBehavior = UIDynamicItemBehavior()
func createAnimatorStuff() {
animator = UIDynamicAnimator(referenceView:self.view);
gravity.gravityDirection = CGVectorMake(0, 0.8)
animator?.addBehavior(gravity)
// We're bouncin' off the walls
collider.translatesReferenceBoundsIntoBoundary = true
animator?.addBehavior(collider)
itemBehavior.friction = 0.7
itemBehavior.elasticity = 0.1
animator?.addBehavior(itemBehavior)
}
func addBoxToBehaviors(box: UIView) {
gravity.addItem(box)
collider.addItem(box)
itemBehavior.addItem(box)
}
//----------------- Core Motion
func gravityUpdated(motion: CMDeviceMotion!, error: NSError!) {
let grav : CMAcceleration = motion.gravity;
let x = CGFloat(grav.x);
let y = CGFloat(grav.y);
var p = CGPointMake(x,y)
if (error != nil) {
NSLog("\(error)")
}
// Have to correct for orientation.
var orientation = UIApplication.sharedApplication().statusBarOrientation;
if(orientation == UIInterfaceOrientation.LandscapeLeft) {
var t = p.x
p.x = 0 - p.y
p.y = t
} else if (orientation == UIInterfaceOrientation.LandscapeRight) {
var t = p.x
p.x = p.y
p.y = 0 - t
} else if (orientation == UIInterfaceOrientation.PortraitUpsideDown) {
p.x *= -1
p.y *= -1
}
var v = CGVectorMake(p.x, 0 - p.y);
gravity.gravityDirection = v;
}
}
编辑2
我只是注意到他们不需要互相接触就可以停止对超重力病毒的反应。
编辑3
好吧，好像是斯威夫特身上的虫子。我在ObjC中实现了相同的功能，没有任何问题。
最佳答案
问题是，重力更新将导致在主线程以外的线程上调用gravityUpdated（）。您应该保持对主线程的UI更新。
要修复它，请切换到gravityUpdated（）中的主线程，如下所示：
func gravityUpdated(motion: CMDeviceMotion!, error: NSError!) {
dispatch_async(dispatch_get_main_queue()) {
// rest of your code here
}
}
或者在主队列上执行CMMotionManager，如下所示：
这条线
let motionQueue = NSOperationQueue()
更改为
let motionQueue = NSOperationQueue.mainQueue()
关于ios - UIDynamicAnimator停止对重力变化使用react，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/29688217/