滾動視圖UIScrollView高級，協議。

#import 

@interface ViewController : UIViewController{//協議函數

    //定義一個滾動視圖成員變量
    UIScrollView * _scrollView;
}

@end

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    //創建滾動視圖
    _scrollView =[[UIScrollView alloc]init];

    //設定滾動視圖的位置
    _scrollView.frame=CGRectMake(10, 50, 300, 400);

    //取消彈動效果
    _scrollView.bounces=NO;

    //是否允許通過點擊屏幕讓滾動視圖響應事件
    //YES:滾動視圖可以接受觸碰事件
    //NO:不接受觸碰事件
//    _scrollView.userInteractionEnabled=NO;
     _scrollView.userInteractionEnabled=YES;

    //設置畫布的大小，縱向效果
    _scrollView.contentSize=CGSizeMake(300, 400*9);

    for(int i=0;i<10;i++){
        //生成圖片名稱
        NSString* strName =[NSString stringWithFormat:@"17_%d.png",i+1];
        UIImage *image = [UIImage imageNamed:strName];
        //創建圖像視圖對象
        UIImageView * iView = [[UIImageView alloc]init];
        //圖像賦值
        iView.image=image;
        //設置圖像視圖在滾動視圖畫布中的位置
        iView.frame=CGRectMake(0, 400*i, 300, 400);
        [_scrollView addSubview:iView];

    }

    [self.view addSubview:_scrollView];

    //取消按頁滾動效果
    _scrollView.pagingEnabled=NO;
//    _scrollView.pagingEnabled=YES;

    //滾動視圖畫布的移動位置，偏移位置
    //功能：決定畫布顯示的最終圖像結果
    _scrollView.contentOffset=CGPointMake(0,0);

    //當前視圖控制器作為代理對象
    _scrollView.delegate=self;
}

-(void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{
//    _scrollView.contentOffset=CGPointMake(0, 0);//點擊空白處，直接跳到設定的坐標位置
    //讓滾動視圖移動到指定位置，動畫移動
    [_scrollView scrollRectToVisible:CGRectMake(0, 0, 300, 400) animated:YES];
}

//當滾動視圖移動時，只要offset坐標發生變化，都會調用此函數
//參數：調用此協議的滾動視圖對象
//可以使用此函數來監控滾動視圖的位置
- (void) scrollViewDidScroll:(UIScrollView *)scrollView{

    NSLog(@"Y=%f",scrollView.contentOffset.y);
}

//當滾動視圖結束拖動時調用此函數
- (void) scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
    NSLog(@"Did End Drag");
}

//滾動視圖即將開始被拖動時
-(void) scrollViewWillBeginDragging:(UIScrollView *)scrollView{
    NSLog(@"WillBeginDrag");
}

//視圖即將結束拖動時調用
-(void) scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset{
    NSLog(@"Will End Drag");
}

//視圖即將減速時調用
-(void) scrollViewWillBeginDecelerating:(UIScrollView *)scrollView{
    NSLog(@"Will Begin Decelerating");
}

//視圖已經結束減速時調用，視圖停止的瞬間調用
-(void) scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    NSLog(@"視圖停止移動");
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

@end