更新:
刚刚找到了一个非常好的 3rd 方库来实现这一点,它叫做 CRMotionView,它运行起来非常流畅,你可以修改很多东西。
这里是github链接:https://github.com/chroman/CRMotionView
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当我第一次看到 Facebook 纸质应用程序时,我也在想同样的视差。但是在玩了我的代码之后,我认为视差不是我们要寻找的。我可能是错的,但我是从基地开始的,陀螺运动管理器。这是我的示例代码:
//import the motion manager frame work first
#import <CoreMotion/CoreMotion.h>
//then need to add a motionManager
@property (strong, nonatomic) CMMotionManager *motionManager;
//you can paste all those codes in view did load
//i added a scroll view on the view controller nib file
self.mainScrollView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
//we don't want it to bounce at each end of the image
self.mainScrollView.bounces = NO;
//and we don't want to allow user scrolling in this case
self.mainScrollView.userInteractionEnabled = NO;
//set up the image view
UIImage *image= [UIImage imageNamed:@"YOUR_IMAGE_NAME"];
UIImageView *movingImageView = [[UIImageView alloc]initWithImage:image];
[self.mainScrollView addSubview:movingImageView];
//set up the content size based on the image size
//in facebook paper case, vertical rotation doesn't do anything
//so we dont have to set up the content size height
self.mainScrollView.contentSize = CGSizeMake(movingImageView.frame.size.width, self.mainScrollView.frame.size.height);
//center the image at intial
self.mainScrollView.contentOffset = CGPointMake((self.mainScrollView.contentSize.width - self.view.frame.size.width) / 2, 0);
//inital the motionManager and detec the Gyroscrope for every 1/60 second
//the interval may not need to be that fast
self.motionManager = [[CMMotionManager alloc] init];
self.motionManager.gyroUpdateInterval = 1/60;
//this is how fast the image should move when rotate the device, the larger the number, the less the roation required.
CGFloat motionMovingRate = 4;
//get the max and min offset x value
int maxXOffset = self.mainScrollView.contentSize.width - self.mainScrollView.frame.size.width;
int minXOffset = 0;
[self.motionManager startGyroUpdatesToQueue:[NSOperationQueue currentQueue]
withHandler:^(CMGyroData *gyroData, NSError *error) {
//since our hands are not prefectly steady
//so it will always have small rotation rate between 0.01 - 0.05
//i am ignoring if the rotation rate is less then 0.1
//if you want this to be more sensitive, lower the value here
if (fabs(gyroData.rotationRate.y) >= 0.1) {
CGFloat targetX = self.mainScrollView.contentOffset.x - gyroData.rotationRate.y * motionMovingRate;
//check if the target x is less than min or larger than max
//if do, use min or max
if(targetX > maxXOffset)
targetX = maxXOffset;
else if (targetX < minXOffset)
targetX = minXOffset;
//set up the content off
self.mainScrollView.contentOffset = CGPointMake(targetX, 0);
}
}];
我在我的设备上对此进行了测试,其工作方式与 facebook 新应用非常相似。
不过,这只是我在半小时内编写的示例代码,可能不是 100% 准确,但希望能给您一些想法。