iOS開發之實現圖片自動切換（類似android畫廊效果）

標籤：

#import "ViewController.h"#define ImageViewCount 5@interface ViewController ()<UIScrollViewDelegate>@property (weak, nonatomic) IBOutlet UIScrollView *imageScrollView;@property (weak, nonatomic) IBOutlet UIPageControl *imageViewPageControl;@property (strong, nonatomic) NSTimer *timer;@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];      [self addImageView2ScrollView];    self.imageScrollView.contentSize = CGSizeMake(self.imageScrollView.frame.size.width * ImageViewCount, 0);    self.imageScrollView.delegate = self;    self.imageScrollView.pagingEnabled = YES;//UIScrollView支援拖動分頁    self.imageViewPageControl.numberOfPages  = ImageViewCount;        [self addScrollTimer];}- (void)rotatePic{    int currentPageIndex = self.imageViewPageControl.currentPage;    if(++currentPageIndex == 5){        currentPageIndex = 0;    }    CGFloat offsetX = currentPageIndex * self.imageScrollView.frame.size.width;    [UIView animateWithDuration:1 animations:^{        self.imageScrollView.contentOffset = CGPointMake(offsetX, 0);    }];}/**添加圖片到imageScrollView*/- (void)addImageView2ScrollView{    CGFloat imageWidth = self.imageScrollView.frame.size.width;    CGFloat imageHeight = self.imageScrollView.frame.size.height;    for(int i = 0;i <= ImageViewCount;i++){        UIImageView *imageInScroll = [[UIImageView alloc] init];        imageInScroll.frame = CGRectMake(i * imageWidth, 0, imageWidth, imageHeight);        imageInScroll.image = [UIImage imageNamed:[NSString stringWithFormat:@"img_%02d",i + 1]];        [self.imageScrollView addSubview:imageInScroll];    }}// 正滾動時執行- (void)scrollViewDidScroll:(UIScrollView *)scrollView{    CGFloat offX = self.imageScrollView.contentOffset.x;//（0，0）距離content內部左上頂點的x軸長度    NSLog(@"~~~~~~~%f ^^^^^^%f", offX, self.imageScrollView.frame.size.width);    int currentPageIndex = (offX + .5f * self.imageScrollView.frame.size.width) / self.imageScrollView.frame.size.width;    self.imageViewPageControl.currentPage = currentPageIndex;}- (void)addScrollTimer{    self.timer = [NSTimer timerWithTimeInterval:2 target:self selector:@selector(rotatePic) userInfo:nil repeats:YES];    [[NSRunLoop mainRunLoop] addTimer:self.timer forMode:NSRunLoopCommonModes];}- (void)removeScrollTimer{    [self.timer invalidate];//釋放定時器    self.timer = nil;}// 開始準備滾動時執行 移除定時滾動操作- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView{    NSLog(@"~~~scrollViewWillBeginDragging");    [self removeScrollTimer];}// 結束滾動後執行 添加定時滾動操作- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{    NSLog(@"~~~scrollViewDidEndDragging");    [self addScrollTimer];}@end

對UIScrollView的運用，以上代碼中有詳細注釋，需注意2點：

1.注意設定contentSize屬性。其中contentSize表示scroll內容尺寸大小

2.注意設定代理UIScrollViewDelegate，才可調用其中的方法

對於定時器NSTimer的運用需注意

1.線上程的loop中添加定時器

2.注意使用完成回收NSTimer

iOS開發之實現圖片自動切換（類似android畫廊效果）