众所周知, 微信中的摇一摇功能: 搜索人/歌曲/电视，同样在一些其他类APP中也有一个摇一摇签到, 摇一摇随机选号等功能，下面以微信摇一摇功能来介绍实现原理.
对于摇一摇功能, 在iOS中系统默认为我们提供了摇一摇的功能检测API. iOS 中既然已经提供了接口, 我们直接调用就好了.
#import <QuartzCore/QuartzCore.h>
#import <AudioToolbox/AudioToolbox.h>
实现原理
1. 监听摇一摇方法
// 摇一摇开始
- (void)motionBegan:(UIEventSubtype)motion withEvent:(nullable UIEvent *)event NS_AVAILABLE_IOS(3_0);
// 摇一摇结束
- (void)motionEnded:(UIEventSubtype)motion withEvent:(nullable UIEvent *)event NS_AVAILABLE_IOS(3_0);
// 摇一摇取消
- (void)motionCancelled:(UIEventSubtype)motion withEvent:(nullable UIEvent *)event NS_AVAILABLE_IOS(3_0);
2. 解决摇一摇失效的情况.
ps: 使用 Xcode6.x 后创建的项目,仅仅实现第一步监听就可以实现,没有遇到这种问题.
- (BOOL)canBecomeFirstResponder {
return YES;
}
3. 摇一摇阶段需要震动及声音.
// 摇动开始
- (void)motionBegan:(UIEventSubtype)motion withEvent:(UIEvent *)event {
AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
}
// 摇动结束
- (void)motionEnded:(UIEventSubtype)motion withEvent:(UIEvent *)event {
if (motion ==UIEventSubtypeMotionShake ) {
// 1.添加摇动动画
// 见第四点, 推荐第四点的方法二
// 2.设置播放音效
SystemSoundID soundID;
NSString *path = [[NSBundle mainBundle ] pathForResource:@"shake_sound_male" ofType:@"wav"];
AudioServicesCreateSystemSoundID((__bridge CFURLRef)[NSURL fileURLWithPath:path], &soundID);
// 添加摇动声音
AudioServicesPlaySystemSound (soundID);
// 3.设置震动
AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);
}
}
4. 摇一摇阶段需要动画效果.
微信的摇一摇功能是先在视图上放一个摇后要显示的图片:手拿手机的图片, 这个图片就是上下两半拼在一起给人一种一张图片的感觉；当检测到摇一摇 捕捉到晃动事件后，上下两张图片分别上下做一个动画移动(上面的一半往上移,下面的往下移)，在completion 里面再移回来.
这里有两种方法:
方法一: 抽出来添加动画效果的方法, 在摇一摇结束方法里添加这个方法.
- (void)addAnimations {
// 让imgup上下移动
CABasicAnimation *translation2 = [CABasicAnimation animationWithKeyPath:@"position"];
translation2.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
translation2.fromValue = [NSValue valueWithCGPoint:CGPointMake(160, 115)];
translation2.toValue = [NSValue valueWithCGPoint:CGPointMake(160, 40)];
translation2.duration = 0.5;
translation2.repeatCount = 1;
translation2.autoreverses = YES;
// 让imagdown上下移动
CABasicAnimation *translation = [CABasicAnimation animationWithKeyPath:@"position"];
translation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
translation.fromValue = [NSValue valueWithCGPoint:CGPointMake(160, 345)];
translation.toValue = [NSValue valueWithCGPoint:CGPointMake(160, 420)];
translation.duration = 0.5;
translation.repeatCount = 1;
translation.autoreverses = YES;
[self.imgDown.layer addAnimation:translation forKey:@"translation"];
[self.imgUp.layer addAnimation:translation2 forKey:@"translation2"];
}
