同时控制多个UIScrollView对象

效果：

分别拖动下方和上方滚动视图

用数组把所有的UIScrollView对象储存起来。

#import "ViewController.h"

@interface ViewController () <UIScrollViewDelegate>

@end

@implementation ViewController

@synthesize scrollViews = _scrollViews;

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    UIImageView *imgViewUp = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"2.png"]];
    UIScrollView *scrollViewUp = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, imgViewUp.frame.size.height)];
    scrollViewUp.contentSize = CGSizeMake(imgViewUp.frame.size.width, imgViewUp.frame.size.height);
    scrollViewUp.bounces = NO;
    scrollViewUp.clipsToBounds = YES;
    scrollViewUp.delegate = self;
    [scrollViewUp addSubview:imgViewUp];
    [self.view addSubview:scrollViewUp];
    /////////////////////////////////////////////////////////////////////////////////
    float height = imgViewUp.frame.size.height;
    UIImageView *imgViewCenter = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"1.png"]];
    imgViewCenter.userInteractionEnabled = YES;
    UIScrollView *scrollViewCenter = [[UIScrollView alloc] initWithFrame:CGRectMake(0, height, self.view.frame.size.width, self.view.frame.size.height-height)];
    scrollViewCenter.contentSize = CGSizeMake(imgViewCenter.frame.size.width, imgViewCenter.frame.size.height);
    scrollViewCenter.bounces = NO;
    scrollViewCenter.clipsToBounds = YES;
    // scrollViewCenter的委托是本对象（ViewController）
    scrollViewCenter.delegate = self;
    [scrollViewCenter addSubview:imgViewCenter];
    [self.view addSubview:scrollViewCenter];
    
    self.scrollViews = [NSArray arrayWithObjects:scrollViewCenter, scrollViewUp, nil];
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    // 枚举UIScrollView对象数组中每一个对象
    for (UIScrollView *view in self.scrollViews) {
        // 对非当前UIScrollView对象进行设置偏移量（contentOffset）
        if (scrollView != view) {
            [view setContentOffset:scrollView.contentOffset];
        }
    }
}

。