iOS：wkwebview自适应高度，修改文字和图片大小

//
//  ViewController.m
//  webTest
//
//  Created by liuyaqiang on 2021/1/8.
//

#import "ViewController.h"
#import <WebKit/WebKit.h>

@interface ViewController ()<UIWebViewDelegate,WKNavigationDelegate,WKUIDelegate>
@property(nonatomic, strong)WKWebView *webView;
@end

@implementation ViewController
- (void)viewDidLoad{
    [super viewDidLoad];
  
    _webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 100, 300,0)];
    _webView.userInteractionEnabled = NO;
    [_webView loadHTMLString:@"<p>导管与热水管、蒸汽管平行敷设时，宜敷设在热水管、蒸汽管的下面，当有困难时，可敷设在其上面；相互间的最小距离宜符合下表规定。</p><p></p><div class=\"media-wrap image-wrap\"><img loop=\"\" autoplay=\"\" controls=\"\" src=\"https://img1.youwen6.com/exam/34cfcb717a0a4a2da3caedadf3e7d483.png\"/></div><p></p>" baseURL:nil];
    [self.view addSubview:_webView];
    self.view.backgroundColor = [UIColor blueColor];
    _webView.scrollView.scrollEnabled = NO;
    [_webView.scrollView addObserver:self forKeyPath:@"contentSize" options:NSKeyValueObservingOptionNew context:nil];
    _webView.navigationDelegate = self;


//    self.automaticallyAdjustsScrollViewInsets = NO;
//    _webView.scrollView.contentInsetAdjustmentBehavior = UIScrollViewContentInsetAdjustmentNever;
}
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation{
    __block CGFloat webViewHeight=0;

    //修改字体大小
    [ webView evaluateJavaScript:@"document.getElementsByTagName('body')[0].style.webkitTextSizeAdjust= '300%'"completionHandler:nil];
    //修改图片大小
    [ webView evaluateJavaScript:@"var script = document.createElement('script');"
    "script.type = 'text/javascript';"
    "script.text = \"function ResizeImages(){ "
    "var myimg,oldwidth;"
    "var maxwidth = 1000.0;" // WKWebView中顯示的圖片寬度
    "for(i=0;i <document.images.length;i++){"
    "myimg = document.images[i];"
    "oldwidth = myimg.width;"
    "myimg.width = maxwidth;"
    "}"
    "}\";"
    "document.getElementsByTagName('head')[0].appendChild(script);ResizeImages();" completionHandler:nil];
}


#pragma mark ------ < KVO > ------
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
    /**  < 法2 >  */
    /**  < loading：防止滚动一直刷新，出现闪屏 >  */
    if ([keyPath isEqualToString:@"contentSize"]) {
        CGRect webFrame = _webView.frame;

        webFrame.size.height = _webView.scrollView.contentSize.height;
        _webView.frame = webFrame;
        NSLog(@"%@",@(_webView.scrollView.contentSize.height));
    }
}
@end