iOS UIWebView下拉刷新实现

网上关于给UITableView实现下拉刷新效果的帖子较多，但是给UIWebView实现的比较少。还好在code4app网站上找到一篇给UIScrollView和UITableView实现下拉刷新的demo【下载地址】。它其中用到的开源控件是EGORefreshTableHeaderView。虽然名字是EGORefreshTableHeaderView，但是它其实可以用于所有UIScrollView，而UIWebView其实也算是一个UIScrollView，所以该控件也是可以用于UIWebView的。

我参照code4app的例子给我的UIWebView加上了下拉刷新的功能，在UIWebView上使用稍微有点不一样的地方。

.h文件中主要代码如下

#import <UIKit/UIKit.h>
#import "EGORefreshTableHeaderView.h"

#define URL_INDEX "http://www.sogou.com"

@interface ViewController : UIViewController <UIWebViewDelegate, UIScrollViewDelegate, EGORefreshTableHeaderDelegate> {
    //下拉视图
    EGORefreshTableHeaderView * _refreshHeaderView;
    //刷新标识，是否正在刷新过程中
    BOOL _reloading;
}

@property(weak, nonatomic) IBOutlet UIWebView *uiWebView;

@end

.m文件中的代码

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

@synthesize uiWebView;

- (void)viewDidLoad
{
    [super viewDidLoad];
    //webview 和 webview 的 scrollView 的委托都设置为self
    self.uiWebView.delegate = self;
    self.uiWebView.scrollView.delegate = self;
    [self loadPage];
    
    //初始化refreshView，添加到webview 的 scrollView子视图中
    if (_refreshHeaderView == nil) {
        _refreshHeaderView = [[EGORefreshTableHeaderView alloc] initWithFrame:CGRectMake(0, 0-self.uiWebView.scrollView.bounds.size.height, self.uiWebView.scrollView.frame.size.width, self.uiWebView.scrollView.bounds.size.height)];
        _refreshHeaderView.delegate = self;
        [self.uiWebView.scrollView addSubview:_refreshHeaderView];
    }
    [_refreshHeaderView refreshLastUpdatedDate];
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
}

//加载网页
- (void)loadPage {
    NSURL *url = [[NSURL alloc] initWithString:@URL_INDEX];
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url];
    [self.uiWebView loadRequest:request];
}

#pragma mark - webview delegate

- (void)webViewDidStartLoad:(UIWebView *)webView {
    _reloading = YES;
}
- (void)webViewDidFinishLoad:(UIWebView *)webView {
    _reloading = NO;
    [_refreshHeaderView egoRefreshScrollViewDataSourceDidFinishedLoading:self.uiWebView.scrollView];
}
- (void)webView:(UIWebView *)webView didFailLoadWithError:(NSError *)error {
    NSLog(@"load page error:%@", [error description]);
    _reloading = NO;
    [_refreshHeaderView egoRefreshScrollViewDataSourceDidFinishedLoading:self.uiWebView.scrollView];
}


#pragma mark -
#pragma mark UIScrollViewDelegate Methods

- (void)scrollViewDidScroll:(UIScrollView *)scrollView{
    [_refreshHeaderView egoRefreshScrollViewDidScroll:scrollView];
}

- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate{
    [_refreshHeaderView egoRefreshScrollViewDidEndDragging:scrollView];
}

-(void)scrollViewDidEndScrollingAnimation:(UIScrollView *)scrollView{
    [_refreshHeaderView egoRefreshScrollViewDidEndDragging:scrollView];
}

#pragma mark -
#pragma mark EGORefreshTableHeaderDelegate Methods

- (void)egoRefreshTableHeaderDidTriggerRefresh:(EGORefreshTableHeaderView*)view{
    
    [self loadPage];
}

- (BOOL)egoRefreshTableHeaderDataSourceIsLoading:(EGORefreshTableHeaderView*)view{
    
    return _reloading; // should return if data source model is reloading
    
}

- (NSDate*)egoRefreshTableHeaderDataSourceLastUpdated:(EGORefreshTableHeaderView*)view{
    
    return [NSDate date]; // should return date data source was last changed
}

@end

这里需要注意的是，几处关于用到UIWebView尺寸的地方不是self.uiWebView.bounds，而应该是self.uiWebView.scrollView.bounds。这也说明UIWebView与UIScrollView不是继承的关系，而是组合的关系。

此Demo的下载地址：

http://code4app.com/ios/UIWebView-%E4%B8%8B%E6%8B%89%E5%88%B7%E6%96%B0/51aee3c16803fa770f000003

参考：

http://code4app.com/ios/scrollview%E5%92%8Ctable%E4%B8%8B%E6%8B%89%E5%88%B7%E6%96%B0/5025fdbe6803fa923e000000