使用加速计用作方向控制器滚动图片（弹珠）

BIDBallView.h

#import <UIKit/UIKit.h>
#import <CoreMotion/CoreMotion.h>

@interface BIDBallView : UIView

@property (nonatomic,assign) CMAcceleration acceleration;
@end

BIDBallView.m

#import "BIDBallView.h"

@interface BIDBallView ()

@property (strong,nonatomic) UIImage *image;
@property (assign,nonatomic) CGPoint currentPoint;
@property (assign,nonatomic) CGPoint previousPoint;
@property (assign,nonatomic) CGFloat ballXVelocity; //Xzhou上的速度
@property (assign,nonatomic) CGFloat ballYVelocity; //Yzhou上的速度

@end

@implementation BIDBallView

-(void)commonInit{

self.image = [UIImage imageNamed:@"pic_客服头像@2x.png"];
self.currentPoint = CGPointMake((self.bounds.size.width /2.0f)+(self.image.size.width/2.0f), (self.bounds.size.height/2.0f)+(self.bounds.size.height/2.0f));

}
-(id)initWithCoder:(NSCoder *)aDecoder{

self = [super initWithCoder:aDecoder];
if (self) {
[self commonInit];
}
return self;
}
-(id)initWithFrame:(CGRect)frame{

self = [super initWithFrame:frame];
if (self) {
[self commonInit];
}
return self;
}
-(void)drawRect:(CGRect)rect{

[self.image drawAtPoint:self.currentPoint]; //绘图代码
}
#pragma Mark

-(void)setCurrentPoint:(CGPoint)newPoint{

self.previousPoint = self.currentPoint; //旧的值存在previousPoint
_currentPoint = newPoint; //新值赋给currentPoint

if (self.currentPoint.x < 0) {
_currentPoint.x = 0;
self.ballXVelocity = 0;

}
if (self.currentPoint.y < 0) {
_currentPoint.y = 0;
self.ballYVelocity = 0;

}

if (self.currentPoint.x > self.bounds.size.width - self.image.size.width) {
_currentPoint.x = self.bounds.size.width - self.image.size.width;
self.ballXVelocity = 0;
}
if (self.currentPoint.y > self.bounds.size.width - self.image.size.width ){
_currentPoint.y = self.bounds.size.width - self.image.size.width;
self.ballYVelocity = 0;
}

CGRect currentRect = CGRectMake(self.currentPoint.x, self.currentPoint.y, self.currentPoint.x+self.image.size.width, self.currentPoint.y+self.image.size.height);
CGRect previousRect = CGRectMake(self.previousPoint.x, self.previousPoint.y, self.previousPoint.x+self.image.size.width, self.previousPoint.y+self.image.size.height);

[self setNeedsDisplayInRect:CGRectUnion(currentRect, previousRect)];
}

-(void)update{
static NSDate *lastUpdateTime = nil;

if (lastUpdateTime != nil) {

NSTimeInterval secondSinceLastDraw = [[NSDate date]timeIntervalSinceDate:lastUpdateTime];

self.ballYVelocity = self.ballYVelocity - (self.acceleration.y * secondSinceLastDraw);
self.ballXVelocity = self.ballXVelocity + (self.acceleration.x *secondSinceLastDraw);

CGFloat xAccel = secondSinceLastDraw * self.ballXVelocity *500;
CGFloat yAccel = secondSinceLastDraw *self.ballYVelocity *500;

self.currentPoint = CGPointMake(self.currentPoint.x + xAccel, self.currentPoint.y + yAccel);
}
lastUpdateTime = [[NSDate alloc]init]; //用当前时间更新最后时间

}
@end

ViewController.m

#import "ViewController.h"
#import "BIDBallView.h"
#import <CoreMotion/CoreMotion.h>

#define kUpdateInterval (1.0f / 60.0f)

@interface ViewController ()

@property (nonatomic,strong)CMMotionManager *motionManager;
@property (nonatomic,strong)NSOperationQueue *queue;

@end

@implementation ViewController

-(void)viewDidLoad{
[super viewDidLoad];

self.motionManager = [[CMMotionManager alloc]init];
self.queue = [[NSOperationQueue alloc]init];

self.motionManager.accelerometerUpdateInterval = kUpdateInterval;
[self.motionManager startAccelerometerUpdatesToQueue:self.queue withHandler:^(CMAccelerometerData * _Nullable accelerometerData, NSError * _Nullable error) {

[(id)self.view setAcceleration:accelerometerData.acceleration];
[self.view performSelectorOnMainThread:@selector(update) withObject:nil waitUntilDone:NO];

}];

}

@end

有需要的可以参考我的github：https://github.com/linxiu/ERBall