最近一個(gè)小伙伴的公司業(yè)務(wù)邏輯上需要做在一個(gè)tableView的header上加載一個(gè)WebView的邏輯躁锁。我們?cè)?code>- (void)webViewDidFinishLoad:(UIWebView *)webView{ CGFloat heights = [[webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"]floatValue]; NSLog(@"高度為：%f",heights); }中獲取的高度確是不正常的、是無(wú)法使用的萄喳。在查閱資料后得知在：web中有很多 圖片未加載完成 的話(huà)，獲取的高度將小于真實(shí)高度种呐，那在它加載完成后拂蝎，內(nèi)容將顯示不全。我們必須換一種方式來(lái)獲取的網(wǎng)頁(yè)的真實(shí)高度霎迫。查閱后得知使用kvo能夠很好的解決的這個(gè)問(wèn)題≌啵現(xiàn)將代碼貼出以供后來(lái)者參考。當(dāng)然后有更好的方案可以再評(píng)論里提出知给，共同進(jìn)步一起提高瓤帚。

代碼示例：

#import "ViewController.h"
//#import "uiweb"
@interface ViewController ()<UIWebViewDelegate,UITableViewDelegate,UITableViewDataSource>{
    CGFloat webViewHeight;
}
@property(nonatomic,strong)UIWebView * webView;
@property(nonatomic,strong)UITableView * listTab;
@end

@implementation ViewController
- (UIWebView *)webView{
    if (!_webView) {
        _webView = [[UIWebView alloc]initWithFrame:self.view.frame];
    }
    return _webView;
}
- (UITableView *)listTab{
    if (!_listTab) {
        _listTab = [[UITableView alloc]init];
    }
    return _listTab;
}
- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self.view addSubview:self.listTab];
    self.listTab.frame = self.view.bounds;
    self.listTab.dataSource = self;
    self.listTab.delegate = self;
    [self.listTab registerClass:[UITableViewCell class] forCellReuseIdentifier:@"ID"];
    
    [self.view addSubview: self.webView];
    NSURL *url = [NSURL URLWithString:@"http://118.178.152.151:8088/platform/news_detail.html?id=32"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [self.webView loadRequest:request];
    self.webView.delegate = self;
    [self.webView.scrollView addObserver:self forKeyPath:@"contentSize" options:NSKeyValueObservingOptionNew context:nil];
    self.webView.scrollView.scrollEnabled = NO;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
    return 5;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
    UITableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:@"ID"];
    cell.backgroundColor = [UIColor redColor];
    return cell;
}
- (void)webViewDidFinishLoad:(UIWebView *)webView{

   
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if ([keyPath isEqualToString:@"contentSize"]) {
        webViewHeight = [[self.webView stringByEvaluatingJavaScriptFromString:@"document.body.offsetHeight"] floatValue];
        CGRect newFrame       = self.webView.frame;
        newFrame.size.height  = webViewHeight;
        self.webView.frame = newFrame;
        NSLog(@"%f",self.webView.frame.size.height);
        [self.listTab setTableHeaderView:self.webView];
    }
}
-(void)viewWillDisappear:(BOOL)antimated{
    [super viewWillDisappear:antimated];
    [self.webView.scrollView removeObserver:self
                                    forKeyPath:@"contentSize" context:nil];
//也可以放在delloc方法中移除
}

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


@end