// // ViewController.m // 仿百度外賣首頁-重力感應 // // Created by Amydom on 16/12/5. // Copyright © 2016年 Amydom. All rights reserved. //  #import "ViewController.h" #import <CoreMotion/CoreMotion.h>  @interface ViewController ()<UIScrollViewDelegate>{      NSTimeInterval updateInterval;   CGFloat setx;//scroll的動態偏移量    } @property (nonatomic,strong) CMMotionManager *mManager;  @property (nonatomic , strong)UIScrollView *myScrollView;  @property (nonatomic , assign)CGFloat offsetX;//初始偏移量  @property (nonatomic , assign)NSInteger offset;   @end  @implementation ViewController  - (void)viewDidAppear:(BOOL)animated_{      [super viewDidAppear:animated_];   //在界面已經顯示后在調用方法(優化)   [self startUpdateAccelerometerResult:0];    }  - (void)viewDidLoad {   [super viewDidLoad];   self.view.backgroundColor = [UIColor whiteColor];   [self createView];    }  - (void)createView{      //collectionView   UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc]init];   UICollectionView *myCollection = [[UICollectionView alloc]initWithFrame:[UIScreen mainScreen].bounds collectionViewLayout:flowLayout];   myCollection.backgroundColor = [UIColor whiteColor];   [self.view addSubview:myCollection];            _myScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0, 22, self.view.frame.size.width, 100)];   _myScrollView.backgroundColor = [UIColor lightGrayColor];   _myScrollView.delegate = self;   [self.view addSubview:_myScrollView];         for (int i = 0; i < 8; i ++) {          NSString *name = [NSString stringWithFormat:@"%d.jpg",i + 1];     UIImageView *image = [[UIImageView alloc]initWithFrame:CGRectMake(5 + 885 * i, 10, 80, 80)];     image.image = [UIImage imageNamed:name];     image.backgroundColor = [UIColor orangeColor];     image.layer.masksToBounds = YES;     image.layer.cornerRadius = 40;     [_myScrollView addSubview:image];     //偏移量為最后 image 的 frame + origin     _myScrollView.contentSize = CGSizeMake (image.frame.size.width + image.frame.origin.x, 10);             }        }  //手指觸碰時 - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{       _offsetX = scrollView.contentOffset.x;   [self stopUpdate];    }  - (void)scrollViewDidScroll:(UIScrollView *)scrollView{      //優化處理   setx = scrollView.contentOffset.x;      _offset = scrollView.contentOffset.x - _offsetX;        if (_offset > 0) {          //left        }else{          //right            }       } //手指離開時 - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{      [self startUpdateAccelerometerResult:0];    }  #pragma mark - 重力感應 - (CMMotionManager *)mManager {   if (!_mManager) {     updateInterval = 1.0/15.0;     _mManager = [[CMMotionManager alloc] init];   }   return _mManager; } //開始 - (void)startUpdateAccelerometerResult:(void (^)(NSInteger))result {    if ([self.mManager isAccelerometerAvailable] == YES) {     //回調會一直調用,建議獲取到就調用下面的停止方法，需要再重新開始，當然如果需求是實時不間斷的話可以等離開頁面之后再stop     [self.mManager setAccelerometerUpdateInterval:updateInterval];     [self.mManager startAccelerometerUpdatesToQueue:[NSOperationQueue currentQueue] withHandler:^(CMAccelerometerData *accelerometerData, NSError *error)      {        double x = accelerometerData.acceleration.x;        double y = accelerometerData.acceleration.y;        if (fabs(y) >= fabs(x))        {//前后          if (y >= 0){            //Down          }          else{            //Portrait          }                  } else { //左右                   if (x >= 0){                        setx += 10;                        if (setx <= 360) {              //由于以10為單位改變 contentOffset, 會出現頓的現象,加上動畫就可解決這個問題              [UIView animateWithDuration:0.1 animations:^{                                _myScrollView.contentOffset = CGPointMake(setx, 0);              }];              //模仿 scroll 的回彈效果              if (setx == 360) {                                [UIView animateWithDuration:0.5 animations:^{                                    _myScrollView.contentOffset = CGPointMake(setx + 50, 0);                                  } completion:^(BOOL finished) {                                    [UIView animateWithDuration:0.5 animations:^{                                        _myScrollView.contentOffset = CGPointMake(setx , 0);                   }];                                  }];                              }                          }else{                            setx = 360;            }                           }else{                        setx -= 10;                        if (setx >= 0) {                            [UIView animateWithDuration:0.1 animations:^{                                _myScrollView.contentOffset = CGPointMake(setx, 0);               }];                            //模仿 scroll 的回彈效果              if (setx == 0) {                                [UIView animateWithDuration:0.5 animations:^{                                    _myScrollView.contentOffset = CGPointMake(setx - 50, 0);                                  } completion:^(BOOL finished) {                                    [UIView animateWithDuration:0.5 animations:^{                                        _myScrollView.contentOffset = CGPointMake(setx, 0);                                      }];                                  }];               }                          }else{                            setx = 0;                          }          }        }      }];   } }  //停止感應方法 - (void)stopUpdate {   if ([self.mManager isAccelerometerActive] == YES)   {     [self.mManager stopAccelerometerUpdates];   } } //離開頁面后停止(移除 mManager) - (void)dealloc {   //制空,防止野指針   _mManager = nil; }   - (void)didReceiveMemoryWarning {   [super didReceiveMemoryWarning];   // Dispose of any resources that can be recreated. }   @end