iOS 7视差效果在我的视图控制器中

我正在用Objective-C为iOS 7开发一个应用程序。我的应用程序中有一个屏幕，上面有几个按钮和一个漂亮的背景图像。(这是一个简单的 xib，UIButtons在UIImageView之上。

我在想，如果这些按钮具有iOS 7主屏幕的视差效果，那就太酷了，所以如果你倾斜手机，你可以看到背景。

如何在自己的应用程序中实现该效果？

在 iOS 7 中，Apple 引入了UIMotionEffect来添加与用户设备方向相关的运动效果。例如，要在主屏幕上模拟视差效果，您可以使用子类UIInterpolatingMotionEffect，如此处所述，只需几行代码即可。

目标-C：

// Set vertical effect
UIInterpolatingMotionEffect *verticalMotionEffect = 
  [[UIInterpolatingMotionEffect alloc] 
  initWithKeyPath:@"center.y"
             type:UIInterpolatingMotionEffectTypeTiltAlongVerticalAxis];
verticalMotionEffect.minimumRelativeValue = @(-10);
verticalMotionEffect.maximumRelativeValue = @(10);
// Set horizontal effect 
UIInterpolatingMotionEffect *horizontalMotionEffect = 
  [[UIInterpolatingMotionEffect alloc] 
  initWithKeyPath:@"center.x"     
             type:UIInterpolatingMotionEffectTypeTiltAlongHorizontalAxis];
horizontalMotionEffect.minimumRelativeValue = @(-10);
horizontalMotionEffect.maximumRelativeValue = @(10);
  
// Create group to combine both
UIMotionEffectGroup *group = [UIMotionEffectGroup new];
group.motionEffects = @[horizontalMotionEffect, verticalMotionEffect];
// Add both effects to your view
[myBackgroundView addMotionEffect:group];

斯威夫特(感谢@Lucas(：

// Set vertical effect
let verticalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.y",
type: .TiltAlongVerticalAxis)
verticalMotionEffect.minimumRelativeValue = -10
verticalMotionEffect.maximumRelativeValue = 10
// Set horizontal effect
let horizontalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.x",
    type: .TiltAlongHorizontalAxis)
horizontalMotionEffect.minimumRelativeValue = -10
horizontalMotionEffect.maximumRelativeValue = 10
// Create group to combine both
let group = UIMotionEffectGroup()
group.motionEffects = [horizontalMotionEffect, verticalMotionEffect]
// Add both effects to your view
myBackgroundView.addMotionEffect(group)

此外，您可以找到一堆库来更轻松地执行此操作或将此功能添加到较旧的iOS版本中：

NGAParallaxMotion(需要iOS 7(。
DVParallaxView(需要iOS 5.0或更高版本和ARC(。
MKParallaxView(在iOS 6.0上测试，需要ARC(。
UIView-MWParallax(在iOS 6.1中测试，需要ARC(。

翻译成swift，

以防有人懒惰。如果您觉得这有用，请投票@veducm回答

@IBOutlet var background : UIImageView!
func parallaxEffectOnBackground() {
    let relativeMotionValue = 50
    var verticalMotionEffect : UIInterpolatingMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.y",
        type: .TiltAlongVerticalAxis)
    verticalMotionEffect.minimumRelativeValue = -relativeMotionValue
    verticalMotionEffect.maximumRelativeValue = relativeMotionValue
    var horizontalMotionEffect : UIInterpolatingMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.x",
        type: .TiltAlongHorizontalAxis)
    horizontalMotionEffect.minimumRelativeValue = -relativeMotionValue
    horizontalMotionEffect.maximumRelativeValue = relativeMotionValue
    var group : UIMotionEffectGroup = UIMotionEffectGroup()
    group.motionEffects = [horizontalMotionEffect, verticalMotionEffect]
    self.background.addMotionEffect(group)
}

@veducm的解决方案可以短一点。如果分别添加 x 轴和 y 轴运动效果，则 x 和 y 运动的 UIMotionEffectGroup 已过时。

UIInterpolatingMotionEffect *motionEffect;
motionEffect = [[UIInterpolatingMotionEffect alloc] initWithKeyPath:@"center.x"
                                                               type:UIInterpolatingMotionEffectTypeTiltAlongHorizontalAxis];
motionEffect.minimumRelativeValue = @(-25);
motionEffect.maximumRelativeValue = @(25);
[bgView addMotionEffect:motionEffect];
motionEffect = [[UIInterpolatingMotionEffect alloc] initWithKeyPath:@"center.y"
                                                               type:UIInterpolatingMotionEffectTypeTiltAlongVerticalAxis];
motionEffect.minimumRelativeValue = @(-25);
motionEffect.maximumRelativeValue = @(25);
[bgView addMotionEffect:motionEffect];

const static CGFloat kCustomIOS7MotionEffectExtent = 10.0; 
- (void)applyMotionEffects:(UIView *YOUR_VIEW) {
     if (NSClassFromString(@"UIInterpolatingMotionEffect")) {
         UIInterpolatingMotionEffect *horizontalEffect = [[UIInterpolatingMotionEffect alloc] initWithKeyPath:@"center.x"
                                                                                                        type:UIInterpolatingMotionEffectTypeTiltAlongHorizontalAxis];
         horizontalEffect.minimumRelativeValue = @(-kCustomIOS7MotionEffectExtent);
         horizontalEffect.maximumRelativeValue = @( kCustomIOS7MotionEffectExtent);
         UIInterpolatingMotionEffect *verticalEffect = [[UIInterpolatingMotionEffect alloc] initWithKeyPath:@"center.y"
                                                                                                      type:UIInterpolatingMotionEffectTypeTiltAlongVerticalAxis];
         verticalEffect.minimumRelativeValue = @(-kCustomIOS7MotionEffectExtent);
         verticalEffect.maximumRelativeValue = @( kCustomIOS7MotionEffectExtent);
         UIMotionEffectGroup *motionEffectGroup = [[UIMotionEffectGroup alloc] init];
         motionEffectGroup.motionEffects = @[horizontalEffect, verticalEffect]; 
         [YOUR_VIEW addMotionEffect:motionEffectGroup];
     }
}

这是一个简单的类别来整合 iOs7+ 的效果：

NSString *const centerX = @"center.x";
NSString *const centerY = @"center.y";
//#define IS_OS_7_OR_LATER    ([[[UIDevice currentDevice] systemVersion] floatValue] >= 7.0)
@implementation UIView (TLMotionEffect)
- (void)addCenterMotionEffectsXYWithOffset:(CGFloat)offset {
//    if(!IS_OS_7_OR_LATER) return;
    if(floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_6_1) return;
    UIInterpolatingMotionEffect *xAxis;
    UIInterpolatingMotionEffect *yAxis;
    xAxis = [[UIInterpolatingMotionEffect alloc] initWithKeyPath:centerX type:UIInterpolatingMotionEffectTypeTiltAlongHorizontalAxis];
    xAxis.maximumRelativeValue = @(offset);
    xAxis.minimumRelativeValue = @(-offset);
    yAxis = [[UIInterpolatingMotionEffect alloc] initWithKeyPath:centerY type:UIInterpolatingMotionEffectTypeTiltAlongVerticalAxis];
    yAxis.minimumRelativeValue = @(-offset);
    yAxis.maximumRelativeValue = @(offset);
    UIMotionEffectGroup *group = [[UIMotionEffectGroup alloc] init];
    group.motionEffects = @[xAxis, yAxis];
    [self addMotionEffect:group];
}
@end

https://github.com/jvenegas/TLMotionEffect

UIMotionEffect 在 iOS 7 上提供了免费的视差实现。

http://www.teehanlax.com/blog/introduction-to-uimotioneffect/

https://github.com/michaeljbishop/NGAParallaxMotion 让您只设置视差强度。

这将帮助那些希望为tableView或collectionView实现视差的人。

首先，为表格视图创建单元格并将图像视图放入其中。

将图像高度设置为略高于单元格高度。如果单元格高度 = 160，则图像高度为 200(要产生视差效果，您可以相应地更改它(

将这两个变量放在您的视图控制器或任何扩展了表视图委托的类中

let imageHeight:CGFloat = 150.0
let OffsetSpeed: CGFloat = 25.0

在同一类中添加以下代码

 func scrollViewDidScroll(scrollView: UIScrollView) {
    //  print("inside scroll")
    if let visibleCells = seriesTabelView.visibleCells as? [SeriesTableViewCell] {
        for parallaxCell in visibleCells {
            var yOffset = ((seriesTabelView.contentOffset.y - parallaxCell.frame.origin.y) / imageHeight) * OffsetSpeedTwo
            parallaxCell.offset(CGPointMake(0.0, yOffset))
        }
    }
}

其中系列TabelView是我的UItableview
现在让我们转到此表视图的单元格并添加以下代码

func offset(offset: CGPoint) {
        posterImage.frame = CGRectOffset(self.posterImage.bounds, offset.x, offset.y)
    }

是
海报图像是我的UIImageView。

如果要将其实现到集合视图，只需将表视图更改为您的集合视图变量

仅此而已。我不确定这是否是最好的方法。但它对我有用。希望它也适合你。如果有任何问题，请告诉我

真的很容易做到，为什么引用复杂的代码。试试吧。加工

在图像视图上查看图像视图的确切大小。默认情况下，视图集 0 的 alpha

。

//MARK: Scroll View Delegate methods
-(void)scrollViewDidScroll:(UIScrollView *)scrollView{
NSLog(@"X: %f Y: %f",scrollView.contentOffset.x,scrollView.contentOffset.y);
CGFloat scrollY = _mainScrollView.contentOffset.y;
CGFloat height = _alphaView.frame.size.height;
CGFloat alphaMonitor = scrollY/height;
_alphaView.alpha = alphaMonitor;
}

Swift 翻译：

// Set vertical effect
let verticalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.y", type: .TiltAlongVerticalAxis)
verticalMotionEffect.minimumRelativeValue = -value
verticalMotionEffect.maximumRelativeValue = value
// Set vertical effect
let horizontalMotionEffect = UIInterpolatingMotionEffect(keyPath: "center.x", type: .TiltAlongHorizontalAxis)
verticalMotionEffect.minimumRelativeValue = -value
verticalMotionEffect.maximumRelativeValue = value
let group = UIMotionEffectGroup()
group.motionEffects = [horizontalMotionEffect, verticalMotionEffect]
self.motionEffect = group
self.addMotionEffect(group)

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