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iOS【终极方案】精准获取webView内容高度,自适应高度
iOS精准获取webView内容高度,自适应高度(cell篇)
#pragma mark-懒加载webView
-(UIWebView *)webView{
if (!_webView) {
// _webView = [[UIWebView alloc] init];
// 1随便多少,不能为0
_webView = [[UIWebView alloc]initWithFrame:CGRectMake(0,0,self.view.frame.size.width,1)];
_webView.delegate = self;
_webView.scrollView.scrollEnabled = NO;
//这个属性不加,webview会显示很大.
_webView.scalesPageToFit = YES;
_webView.opaque =NO;
//预先加载url
[_webView loadRequest:[[NSURLRequest alloc] initWithURL:[NSURL URLWithString:[NSString stringWithFormat:@"%@/api/product/piclist?item_id=%@",SERVER,self.model.itemid]]]];
//给webView的scrollView的contentSize属性添加监听,每当内容发生变化,contentSize一定会跟着变,捕获这个变动
// [self.webView.scrollView addObserver:self forKeyPath:@"contentSize" options:(NSKeyValueObservingOptionNew) context:nil];
[self.webView.scrollView addObserver:self forKeyPath:@"contentSize" options:NSKeyValueObservingOptionOld | NSKeyValueObservingOptionNew context:nil];
}
return _webView;
}
- (void)viewDidLoad {
[super viewDidLoad];
[self.view addSubview:self.webView];
}
#pragma mark - UIWebView Delegate Methods
-(void)webViewDidFinishLoad:(UIWebView *)webView
{
[[MBProgressHUD HUDForView:self.view] removeFromSuperview];
// //获取到webview的高度
//// CGFloat height = [[webView stringByEvaluatingJavaScriptFromString:@"document.documentElement.scrollHeight"]floatValue];
// self.webViewHeight = [[self.webView stringByEvaluatingJavaScriptFromString:@"document.body.scrollHeight"] floatValue];
// CGSize webSize = [webView sizeThatFits:CGSizeZero];
// [webView mas_updateConstraints:^(MASConstraintMaker *make) {
// make.height.equalTo(@(webSize.height));
// }];
// cellhight = self.webViewHeight;
// [self.tableView reloadData];
}
- (void)webViewDidStartLoad:(UIWebView *)webView
{
NSLog(@"webViewDidStartLoad");
// [MBProgressHUD showHUDAddedTo:self.view animated:YES];
}
- (void)webView:(UIWebView *)webView didFailLoadWithError:(nonnull NSError *)error
{
NSLog(@"didFailLoadWithError===%@", error);
isOpen = !isOpen;
[[MBProgressHUD HUDForView:self.view] removeFromSuperview];
[AMShowMessage showMessage:@"加载失败" withDuration:2];
[self.tableView reloadData];
}
#pragma mark-监听的处理1、监听tableview偏移(控制导航的透明度)2、监听webView.scrollView的contentSize的变化
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
if ([keyPath isEqualToString:@"contentOffset"])
{
UIButton * bottom = [self.view viewWithTag:1000];
CGPoint offset = [change[NSKeyValueChangeNewKey] CGPointValue];
CGFloat alpha = offset.y/NAVIGATION_BAR_HEIGHT >1.0f ? 1:offset.y/NAVIGATION_BAR_HEIGHT;
//设置一个颜色并转化为图片
UIImage *image = [self imageWithColor:[UIColor colorWithRed:1.0 green:1.0 blue:1.0 alpha:alpha]];
self.navigationView.image = image;
self.navigationController.navigationBar.alpha = alpha;
self.topView.backgroundColor = [UIColor colorWithPatternImage:image];
self.topView.alpha = alpha;
if (offset.y > 0) {
self.navigationView.isAlphZero = NO;
bottom.hidden = NO;
}else{
self.navigationView.isAlphZero = YES;
bottom.hidden = YES;
}
}
if ([keyPath isEqualToString:@"contentSize"]) {
//通过JS代码获取webview的内容高度
//self.webViewHeight = [[self.webView stringByEvaluatingJavaScriptFromString:@"document.body.scrollHeight"] floatValue];
//通过webview的contentSize获取内容高度
//self.webViewHeight = [self.showWebView.scrollView contentSize].height;
CGRect frame = self.webView.frame;
//通过webview的contentSize获取内容高度
frame.size.height = self.webView.scrollView.contentSize.height;
//这里获取webView的高度
_webViewHeight = frame.size.height;
NSLog(@"%f",frame.size.height);
cellhight =_webViewHeight;
CGSize webSize = [self.webView sizeThatFits:CGSizeZero];
[self.webView mas_updateConstraints:^(MASConstraintMaker *make) {
make.height.equalTo(@(webSize.height));
}];
[self.tableView reloadData];
}
}
反思:
1、在webViewDidFinishLoad方法中获取webView的内容高度,会导致获取的内容高度不精确,因为webViewDidFinishLoad代理方法被调用时,页面并不一定完全展现完成,可能有图片还未加载出来,导致此时获取的高度是并不是最终高度,过会儿图片加载出来后,浏览器会重新排版,而我们在这之前给了一个错误高度,导致显示异常。所以需要在监听到webView.scrollView的contentSize变化时,获取到的webView的内容高度才时精确的。
#pragma mark - UIWebView Delegate Methods
-(void)webViewDidFinishLoad:(UIWebView *)webView
{
[[MBProgressHUD HUDForView:self.view] removeFromSuperview];
// //获取到webview的高度
//// CGFloat height = [[webView stringByEvaluatingJavaScriptFromString:@"document.documentElement.scrollHeight"]floatValue];
// self.webViewHeight = [[self.webView stringByEvaluatingJavaScriptFromString:@"document.body.scrollHeight"] floatValue];
// CGSize webSize = [webView sizeThatFits:CGSizeZero];
// [webView mas_updateConstraints:^(MASConstraintMaker *make) {
// make.height.equalTo(@(webSize.height));
// }];
// cellhight = self.webViewHeight;
[self.tableView reloadData];
}
2、实例化创建webView的时候,必须设置frame值,否值不显示
// 高度随便多少,可以为1,但不能为0,为0 则webView不显示
_webView = [[UIWebView alloc]initWithFrame:CGRectMake(0,0,self.view.frame.size.width,1)];
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