ios开发——实用技术篇&图片无限滚动和自动滚动

浏览数：32 / 时间：2015年06月11日

初始化项目

1:自定义一个集成自Collection的Cell

1 #import <UIKit/UIKit.h>
2 @class iCocosNews;
3 @interface iCocosNewsCell : UICollectionViewCell
4 @property (nonatomic, strong) iCocosNews *news;
5 @end

 1 #import "iCocosNewsCell.h"
 2 #import "iCocosNews.h"
 3 
 4 @interface iCocosNewsCell()
 5 @property (weak, nonatomic) IBOutlet UILabel *titleLabel;
 6 @property (weak, nonatomic) IBOutlet UIImageView *iconView;
 7 @end
 8 
 9 @implementation iCocosNewsCell
10 - (void)setNews:(iCocosNews *)news
11 {
12     _news = news;
13     
14     self.iconView.image = [UIImage imageNamed:news.icon];
15     self.titleLabel.text = NSString(@"  %@", news.title);
16 }
17 
18 @end

2:对应要显示的模型数据（只需要实现.h文件）

1 #import <Foundation/Foundation.h>
2 
3 @interface iCocosNews : NSObject
4 @property (copy, nonatomic) NSString *title;
5 @property (copy, nonatomic) NSString *icon;
6 @end

一：无限滚动

:控制器里面直接使用

 1 #import "iCocosNewsViewController.h"
 2 #import "iCocosNewsCell.h"
 3 #import "MJExtension.h"
 4 #import "iCocosNews.h"
 5 
 6 #define iCocosCellIdentifier @"news"
 7 #define iCocosMaxSections 100
 8 
 9 @interface iCocosNewsViewController () <UICollectionViewDataSource, UICollectionViewDelegate>
10 @property (weak, nonatomic) IBOutlet UICollectionView *collectionView;
11 @property (nonatomic, strong) NSArray *newses;
12 @end
13 
14 @implementation iCocosNewsViewController
15 
16 //- (NSMutableArray *)newses
17 //{
18 //    if (_newses == nil) {
19 //        self.newses = [NSMutableArray array];
20 //        
21 //        for (int i = 0; i<200; i++) {
22 //            NSArray *array = [iCocosNews objectArrayWithFilename:@"newses.plist"];
23 //            [self.newses addObjectsFromArray:array];
24 //        }
25 //    }
26 //    return _newses;
27 //}
28 
29 - (NSArray *)newses
30 {
31     if (_newses == nil) {
32         self.newses = [iCocosNews objectArrayWithFilename:@"newses.plist"];
33     }
34     return _newses;
35 }
36 
37 - (void)viewDidLoad
38 {
39     [super viewDidLoad];
40     
41     // 注册cell
42     [self.collectionView registerNib:[UINib nibWithNibName:@"iCocosNewsCell" bundle:nil] forCellWithReuseIdentifier:iCocosCellIdentifier];
43     
44 //    [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:500 inSection:0] atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
45     
46     [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:iCocosMaxSections/2] atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
47 }
48 
49 #pragma mark - UICollectionViewDataSource
50 - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
51 {
52     return self.newses.count;
53 }
54 
55 - (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
56 {
57     return iCocosMaxSections;
58 }
59 
60 - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
61 {
62     iCocosNewsCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:iCocosCellIdentifier forIndexPath:indexPath];
63     
64     cell.news = self.newses[indexPath.item];
65     
66     return cell;
67 }
68 
69 
70 @end

：需要使用MJExtension实现模型数据的转换

二：自动滚动

:控制器里面直接使用

  1 #import "iCocosNewsViewController.h"
  2 #import "iCocosNewsCell.h"
  3 #import "MJExtension.h"
  4 #import "iCocosNews.h"
  5 
  6 #define iCocosCellIdentifier @"news"
  7 #define iCocosMaxSections 100
  8 
  9 @interface iCocosNewsViewController () <UICollectionViewDataSource, UICollectionViewDelegate>
 10 @property (weak, nonatomic) IBOutlet UICollectionView *collectionView;
 11 @property (nonatomic, weak) IBOutlet UIPageControl *pageContol;
 12 @property (nonatomic, strong) NSArray *newses;
 13 @property (nonatomic, strong) NSTimer *timer;
 14 @end
 15 
 16 @implementation iCocosNewsViewController
 17 
 18 - (NSArray *)newses
 19 {
 20     if (_newses == nil) {
 21         self.newses = [iCocosNews objectArrayWithFilename:@"newses.plist"];
 22         self.pageContol.numberOfPages = self.newses.count;
 23     }
 24     return _newses;
 25 }
 26 
 27 - (void)viewDidLoad
 28 {
 29     [super viewDidLoad];
 30     
 31     // 注册cell
 32     [self.collectionView registerNib:[UINib nibWithNibName:@"iCocosNewsCell" bundle:nil] forCellWithReuseIdentifier:iCocosCellIdentifier];
 33     
 34     // 默认显示最中间的那组
 35     [self.collectionView scrollToItemAtIndexPath:[NSIndexPath indexPathForItem:0 inSection:iCocosMaxSections/2] atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
 36     
 37     // 添加定时器
 38     [self addTimer];
 39 }
 40 
 41 /**
 42  *  添加定时器
 43  */
 44 - (void)addTimer
 45 {
 46     NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(nextPage) userInfo:nil repeats:YES];
 47     [[NSRunLoop mainRunLoop] addTimer:timer forMode:NSRunLoopCommonModes];
 48     self.timer = timer;
 49 }
 50 
 51 /**
 52  *  移除定时器
 53  */
 54 - (void)removeTimer
 55 {
 56     // 停止定时器
 57     [self.timer invalidate];
 58     self.timer = nil;
 59 }
 60 
 61 - (NSIndexPath *)resetIndexPath
 62 {
 63     // 当前正在展示的位置
 64     NSIndexPath *currentIndexPath = [[self.collectionView indexPathsForVisibleItems] lastObject];
 65     // 马上显示回最中间那组的数据
 66     NSIndexPath *currentIndexPathReset = [NSIndexPath indexPathForItem:currentIndexPath.item inSection:iCocosMaxSections/2];
 67     [self.collectionView scrollToItemAtIndexPath:currentIndexPathReset atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
 68     return currentIndexPathReset;
 69 }
 70 
 71 /**
 72  *  下一页
 73  */
 74 - (void)nextPage
 75 {
 76     // 1.马上显示回最中间那组的数据
 77     NSIndexPath *currentIndexPathReset = [self resetIndexPath];
 78     
 79     // 2.计算出下一个需要展示的位置
 80     NSInteger nextItem = currentIndexPathReset.item + 1;
 81     NSInteger nextSection = currentIndexPathReset.section;
 82     if (nextItem == self.newses.count) {
 83         nextItem = 0;
 84         nextSection++;
 85     }
 86     NSIndexPath *nextIndexPath = [NSIndexPath indexPathForItem:nextItem inSection:nextSection];
 87     
 88     // 3.通过动画滚动到下一个位置
 89     [self.collectionView scrollToItemAtIndexPath:nextIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:YES];
 90 }
 91 
 92 #pragma mark - UICollectionViewDataSource
 93 - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
 94 {
 95     return self.newses.count;
 96 }
 97 
 98 - (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
 99 {
100     return iCocosMaxSections;
101 }
102 
103 - (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
104 {
105     iCocosNewsCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:iCocosCellIdentifier forIndexPath:indexPath];
106     
107     cell.news = self.newses[indexPath.item];
108     
109     return cell;
110 }
111 
112 #pragma mark  - UICollectionViewDelegate
113 /**
114  *  当用户即将开始拖拽的时候就调用
115  */
116 - (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
117 {
118     [self removeTimer];
119 }
120 
121 /**
122  *  当用户停止拖拽的时候就调用
123  */
124 - (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
125 {
126 //    NSLog(@"scrollViewDidEndDragging--松开");
127     [self addTimer];
128 }
129 
130 - (void)scrollViewDidScroll:(UIScrollView *)scrollView
131 {
132     int page = (int)(scrollView.contentOffset.x / scrollView.bounds.size.width + 0.5) % self.newses.count;
133     self.pageContol.currentPage = page;
134 }
135 @end

最后给大家介绍一种常用的截图方法

 1     // 1.开启图形上下文
 2     CGSize imageSize = self.view.bounds.size;
 3     UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0.0);
 4     
 5     // 2.将某个view的所有内容渲染到图形上下文中
 6     CGContextRef context = UIGraphicsGetCurrentContext();
 7     [self.view.layer renderInContext:context];
 8     
 9     // 3.取得图片
10     UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
11     
12     CGImageRef subimageRef = CGImageCreateWithImageInRect(image.CGImage, CGRectMake(0, 0, 640, 480));
13     UIImage *subImage = [UIImage imageWithCGImage:subimageRef];
14     [UIImagePNGRepresentation(subImage) writeToFile:@"/Users/apple/Desktop/view.png" atomically:YES];
15     
16     // 4.关闭上下文
17     UIGraphicsEndImageContext();