iOS UITableView加载webView高度自适应

众所周知iOS8后苹果增加了WKWebView,在这之前大家使用的都是UIWebView,刚出来之后我也一直在使用UIWebView,最近听说UIWebView以后会过期，所以本文以WKWeBView为例

实现原理：

自定义UITableViewCell， cell上添加scrollView，再将WKWebView添加到scrollView，通过KVO监听webView.scrollView的contentSize值的变化来获取scrollView的高度，从而更新tableViewCell的行高

实现细节：

为了让web页面中的元素都适应屏幕的宽度显示，需要对WKWebView进行一下设置，原理是加载js代码，然后通过js来设置webview中的元素大小：

实现过程：

//
//  ViewController.m
//  HQWebView
//
//  Created by admin on 2017/7/18.
//  Copyright © 2017年 judian. All rights reserved.
//

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

@interface ViewController ()<UITableViewDelegate, UITableViewDataSource, WKUIDelegate, WKNavigationDelegate>

@property (nonatomic, strong) UITableView *tableView;

@property (nonatomic, strong) UIScrollView *scrollView;

@property (nonatomic, strong) WKWebView *webView;

@property (nonatomic, assign) CGFloat webViewHeight;

@end

static NSString *reuseDefaultCell = @"DefaultCell";
static NSString *reuseWebCell = @"WebCell";

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    
    self.webViewHeight = 0.0;
    
    [self creatWebView];
    
    self.tableView = [[UITableView alloc] initWithFrame:self.view.frame style:UITableViewStylePlain];
    self.tableView.delegate = self;
    self.tableView.dataSource = self;
    self.tableView.showsHorizontalScrollIndicator = NO;
    self.tableView.showsVerticalScrollIndicator = NO;
    self.tableView.separatorStyle = UITableViewCellSeparatorStyleNone;
    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:reuseWebCell];
    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:reuseDefaultCell];

    [self.view addSubview:self.tableView];
}

#pragma mark -------创建webView-------
- (void)creatWebView {
    WKWebViewConfiguration *wkWebConfig = [[WKWebViewConfiguration alloc] init];
    WKUserContentController *wkUController = [[WKUserContentController alloc] init];
    wkWebConfig.userContentController = wkUController;
    //自适应屏幕的宽度js
    NSString *jSString = @"var meta = document.createElement('meta'); meta.setAttribute('name', 'viewport'); meta.setAttribute('content', 'width=device-width'); document.getElementsByTagName('head')[0].appendChild(meta);";
    WKUserScript *wkUserScript = [[WKUserScript alloc] initWithSource:jSString injectionTime:WKUserScriptInjectionTimeAtDocumentEnd forMainFrameOnly:YES];
    //添加js调用
    [wkUController addUserScript:wkUserScript];
    
    self.webView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 1) configuration:wkWebConfig];
    self.webView.backgroundColor = [UIColor clearColor];
    self.webView.opaque = NO;
    self.webView.userInteractionEnabled = YES;
    self.webView.scrollView.bounces = NO;
    self.webView.UIDelegate = self;
    self.webView.navigationDelegate = self;
    [self.webView sizeToFit];
    //监听webView  contentSize 值得变化
    [self.webView.scrollView addObserver:self forKeyPath:@"contentSize" options:NSKeyValueObservingOptionNew context:nil];
    NSURL *url = [NSURL URLWithString:@"https://www.baidu.com"];
    NSURLRequest *request = [NSURLRequest requestWithURL:url];
    [self.webView loadRequest:request];
    
    self.scrollView = [[UIScrollView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, 1)];
    [self.scrollView addSubview:self.webView];
}
#pragma 监听webView  contentSize 值的变化
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSKeyValueChangeKey,id> *)change context:(void *)context {
    if ([keyPath isEqualToString:@"contentSize"]) {
        //方法一
        UIScrollView *scrollView = (UIScrollView *)object;
        CGFloat height = scrollView.contentSize.height;
        self.webViewHeight = height;
        self.webView.frame = CGRectMake(0, 0, self.view.frame.size.width, height);
        self.scrollView.frame = CGRectMake(0, 0, self.view.frame.size.width, height);
        self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width, height);
        [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:[NSIndexPath indexPathForRow:3 inSection:0], nil] withRowAnimation:UITableViewRowAnimationNone];
        
        /*
        //方法二
        [_webView evaluateJavaScript:@"document.body.offsetHeight" completionHandler:^(id _Nullable result, NSError * _Nullable error) {
            CGFloat height = [result doubleValue] + 20;
            self.webViewHeight = height;
            self.webView.frame = CGRectMake(0, 0, self.view.frame.size.width, height);
            self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width, height);
            [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObjects:[NSIndexPath indexPathForRow:3 inSection:0], nil]  withRowAnimation:UITableViewRowAnimationNone];
        }];
         */
    }
}

#pragma mark -------UItableViewDelegate-------
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return 15;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    switch (indexPath.row) {
        case 3:
            return _webViewHeight;
            break;
        default:
            return 50;
            break;
    }
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    switch (indexPath.row) {
        case 3: {
            UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:reuseWebCell];
            [cell.contentView addSubview:self.scrollView];
            return cell;
        }
            break;
            
        default: {
            UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:reuseDefaultCell];
            cell.textLabel.text = [NSString stringWithFormat:@"普通cell, 编号：%ld", indexPath.row];
            return cell;
        }
            break;
    }
}
@end

github下载地址：https://github.com/yanhaiqiang/HQWebViewFit.git  别忘了给个star啊