iOS開發UI篇—無限輪播(功能完善)

iOS開發UI篇—無限輪播(功能完善)app

1、自動滾動oop

添加並設置一個定時器,每一個2.0秒,就跳轉到下一條。佈局

  獲取當前正在展現的位置。動畫

 1     [self addNSTimer];
 2 }
 3 
 4 -(void)addNSTimer
 5 {
 6 //    NSTimer timerWithTimeInterval:<#(NSTimeInterval)#> target:<#(id)#> selector:<#(SEL)#> userInfo:<#(id)#> repeats:<#(BOOL)#>
 7     [NSTimer scheduledTimerWithTimeInterval:1.5 target:self selector:@selector(nextPage) userInfo:nil repeats:YES];
 8 }
 9 -(void)nextPage
10 {
11     NSLog(@"%@",[self.collectinView indexPathsForVisibleItems]); 12 //    NSIndexPath *currentIndexPath=[[self.collectinView indexPathsForVisibleItems]lastObject];
13 }

  打印查看:atom

  

實現步驟:spa

(1)添加並設置定時器code

(2)設置定時器的調用方法blog

  1)獲取當前正在展現的位置繼承

  2)計算出下一個須要展現的位置開發

  3)經過動畫滾動到下一個位置

  注意點:須要進行判斷。

實現代碼:

 1 - (void)viewDidLoad
 2 {
 3     [super viewDidLoad];
 4     //註冊cell
 5 //    [self.collectinView registerClass:[YYimageCell class] forCellWithReuseIdentifier:YYCell];
 6     [self.collectinView registerNib:[UINib nibWithNibName:@"YYcell" bundle:nil] forCellWithReuseIdentifier:YYIDCell];
 7     
 8     
 9      [self.collectinView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:50] atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
10      [self addNSTimer];
11 }
12 
13 -(void)addNSTimer
14 {
15 //    NSTimer timerWithTimeInterval:<#(NSTimeInterval)#> target:<#(id)#> selector:<#(SEL)#> userInfo:<#(id)#> repeats:<#(BOOL)#>
16     
17    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.5 target:self selector:@selector(nextPage) userInfo:nil repeats:YES];
18     //添加到runloop中
19     [[NSRunLoop mainRunLoop]addTimer:timer forMode:NSRunLoopCommonModes];
20 }
21 -(void)nextPage
22 {
23 //    NSLog(@"%@",[self.collectinView indexPathsForVisibleItems]);
24         //1)獲取當前正在展現的位置
25     NSIndexPath *currentIndexPath=[[self.collectinView indexPathsForVisibleItems]lastObject];
26     
27        //2)計算出下一個須要展現的位置
28     NSInteger nextItem=currentIndexPath.item+1;
29     NSInteger nextSection=currentIndexPath.section;
30     if (nextItem==self.news.count) {
31         nextItem=0;
32         nextSection++;
33     }
34     NSIndexPath *nextIndexPath=[NSIndexPath indexPathForItem:nextItem inSection:nextSection];
35     
36       //3)經過動畫滾動到下一個位置
37      [self.collectinView scrollToItemAtIndexPath:nextIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
38 }

定時器的說明:

  當用戶在處理其餘事情的時候,定時器會中止工做。應該把定時器添加到runloop中,告訴系統在處理其餘事情的時候分一部分空間給它。

 

2、設置頁碼

  在storyboard中添加一個頁碼控件。

實現代碼:  

 1 #pragma mark-懶加載
 2 -(NSArray *)news
 3 {
 4     if (_news==nil) {
 5         _news=[YYnews objectArrayWithFilename:@"newses.plist"];
 6         self.pageControl.numberOfPages=self.news.count;  7     }
 8     return _news;
 9 }
10 
11 - (void)viewDidLoad
12 {
13     [super viewDidLoad];
14     //註冊cell
15 //    [self.collectinView registerClass:[YYimageCell class] forCellWithReuseIdentifier:YYCell];
16     [self.collectinView registerNib:[UINib nibWithNibName:@"YYcell" bundle:nil] forCellWithReuseIdentifier:YYIDCell];
17     
18     
19      [self.collectinView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:50] atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
20     [self addNSTimer];
21 }
22 
23 -(void)addNSTimer
24 {
25 //    NSTimer timerWithTimeInterval:<#(NSTimeInterval)#> target:<#(id)#> selector:<#(SEL)#> userInfo:<#(id)#> repeats:<#(BOOL)#>
26     
27    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:1.5 target:self selector:@selector(nextPage) userInfo:nil repeats:YES];
28     //添加到runloop中
29     [[NSRunLoop mainRunLoop]addTimer:timer forMode:NSRunLoopCommonModes];
30 }
31 -(void)nextPage
32 {
33 //    NSLog(@"%@",[self.collectinView indexPathsForVisibleItems]);
34         //1)獲取當前正在展現的位置
35     NSIndexPath *currentIndexPath=[[self.collectinView indexPathsForVisibleItems]lastObject];
36     
37        //2)計算出下一個須要展現的位置
38     NSInteger nextItem=currentIndexPath.item+1;
39     NSInteger nextSection=currentIndexPath.section;
40     if (nextItem==self.news.count) {
41         nextItem=0;
42         nextSection++;
43     }
44     NSIndexPath *nextIndexPath=[NSIndexPath indexPathForItem:nextItem inSection:nextSection];
45     
46       //3)經過動畫滾動到下一個位置
47      [self.collectinView scrollToItemAtIndexPath:nextIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
48     
49     //4)設置頁碼
50     self.pageControl.currentPage=nextItem; 51 }

 自動滾動,頁碼的實現效果:

3、完善

說明:監聽collectionView的滾動,當手動觸摸collectionView,嘗試拖拽的時候,把定時器停掉,當手指移開的時候,重啓定時器。

完整的實現代碼:

  1 //
  2 //  YYViewController.m
  3 //  07-無限滾動(循環利用)
  4 //
  5 //  Created by apple on 14-8-3.
  6 //  Copyright (c) 2014年 yangyong. All rights reserved.
  7 //
  8 
  9 #import "YYViewController.h"
 10 #import "MJExtension.h"
 11 #import "YYnews.h"
 12 #import "YYcell.h"
 13 
 14 #define YYIDCell @"cell"
 15 //注意:這裏須要考慮用戶的手動拖拽
 16 #define YYMaxSections 100
 17 @interface YYViewController ()<UICollectionViewDataSource,UICollectionViewDelegate>
 18 @property (weak, nonatomic) IBOutlet UICollectionView *collectinView;
 19 @property(nonatomic,strong)NSArray *news;
 20 @property (weak, nonatomic) IBOutlet UIPageControl *pageControl;
 21 @property(nonatomic,strong)NSTimer *timer;
 22 
 23 @end
 24 
 25 @implementation YYViewController
 26 
 27 #pragma mark-懶加載
 28 -(NSArray *)news
 29 {
 30     if (_news==nil) {
 31         _news=[YYnews objectArrayWithFilename:@"newses.plist"];
 32         self.pageControl.numberOfPages=self.news.count;
 33     }
 34     return _news;
 35 }
 36 
 37 - (void)viewDidLoad
 38 {
 39     [super viewDidLoad];
 40     //註冊cell
 41 //    [self.collectinView registerClass:[YYimageCell class] forCellWithReuseIdentifier:YYCell];
 42     [self.collectinView registerNib:[UINib nibWithNibName:@"YYcell" bundle:nil] forCellWithReuseIdentifier:YYIDCell];
 43     
 44     
 45      [self.collectinView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:50] atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
 46     [self addNSTimer];
 47 }
 48 
 49 //添加定時器
 50 -(void)addNSTimer
 51 {
 52    NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:0.5 target:self selector:@selector(nextPage) userInfo:nil repeats:YES];
 53     //添加到runloop中
 54     [[NSRunLoop mainRunLoop]addTimer:timer forMode:NSRunLoopCommonModes];
 55     self.timer=timer;
 56 }
 57 
 58 //刪除定時器
 59 -(void)removeNSTimer
 60 {
 61     [self.timer invalidate];
 62     self.timer=nil;
 63 }
 64 
 65 //自動滾動
 66 -(void)nextPage
 67 {
 68         //1獲取當前正在展現的位置
 69     NSIndexPath *currentIndexPath=[[self.collectinView indexPathsForVisibleItems]lastObject];
 70     
 71     //立刻顯示回最中間那組的數據
 72     NSIndexPath *currentIndexPathRest=[NSIndexPath indexPathForItem:currentIndexPath.item inSection:YYMaxSections/2];
 73     [self.collectinView scrollToItemAtIndexPath:currentIndexPathRest atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
 74     
 75        //2計算出下一個須要展現的位置
 76     NSInteger nextItem=currentIndexPathRest.item+1;
 77     NSInteger nextSection=currentIndexPathRest.section;
 78     if (nextItem==self.news.count) {
 79         nextItem=0;
 80         nextSection++;
 81     }
 82     NSIndexPath *nextIndexPath=[NSIndexPath indexPathForItem:nextItem inSection:nextSection];
 83     
 84       //3經過動畫滾動到下一個位置
 85      [self.collectinView scrollToItemAtIndexPath:nextIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
 86     
 87 //    //4)設置頁碼
 88 //    self.pageControl.currentPage=nextItem;
 89 }
 90 
 91 #pragma mark- UICollectionViewDataSource
 92 //一共多少組,默認爲1組
 93 -(NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
 94 {
 95     return YYMaxSections;
 96 }
 97 -(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
 98 {
 99     return self.news.count;
100 }
101 
102 -(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
103 {
104     YYcell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:YYIDCell forIndexPath:indexPath];
105     cell.news=self.news[indexPath.item];
106     NSLog(@"%p,%d",cell,indexPath.item);
107     return cell;
108 }
109 
110 #pragma mark-UICollectionViewDelegate
111 //當用戶開始拖拽的時候就調用
112 -(void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
113 {
114     [self removeNSTimer];
115 }
116 //當用戶中止拖拽的時候調用
117 -(void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
118 {
119     [self addNSTimer];
120 }
121 //設置頁碼
122 -(void)scrollViewDidScroll:(UIScrollView *)scrollView
123 {
124     int page=(int)(scrollView.contentOffset.x/scrollView.frame.size.width+0.5)%self.news.count;
125     self.pageControl.currentPage=page;
126 }
127 @end

補充說明:

  實現瀑布流最理想的作法是繼承UIScrollView,不建議使用多個UITableView的方式實現(這種方式沒法實現cell的循環利用,且禁止了cell的滾動時間後,總體的tableView須要隨着滾動會出現空白)。

  也能夠使用collectionView來實現,但使用這種方法須要自定義collectionView的佈局(流水佈局)

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