iOS UIWebView 加载进度条的使用-WKWebView的使用，更新2017.6.26

1、由于项目中加载网络插件，直接使用了webview加载。使用了三方NJKWebViewProgress进度条的使用，近期在测试时发现，网络缓慢时出现白屏，有卡顿现象。

于是采用了WKWebView进行加载，KVO监听下载进度

//  ViewController.m

#import "ViewController.h"

#import <WebKit/WebKit.h>
#import <WebKit/WKWebView.h>

#define SCREEN_WIDTH ([UIScreen mainScreen].bounds.size.width)
#define SCREEN_HEIGHT ([UIScreen mainScreen].bounds.size.height)

#define IPHONEHIGHT(b) [UIScreen mainScreen].bounds.size.height*((b)/1334.0)
#define IPHONEWIDTH(a) [UIScreen mainScreen].bounds.size.width*((a)/750.0)

static void *WkwebBrowserContext = &WkwebBrowserContext;
@interface ViewController ()<WKNavigationDelegate,WKUIDelegate,WKScriptMessageHandler,UINavigationControllerDelegate,UINavigationBarDelegate>
{
    UIButton * back;
    UILabel * labeltitle;//webview显示前的title

}
@property (nonatomic, strong) WKWebView *wkWebView;
//设置加载进度条
@property (nonatomic,strong) UIProgressView *progressView;
@end

@implementation ViewController

-(void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];

    self.tabBarController.tabBar.hidden = YES;
    self.navigationController.navigationBar.hidden= NO;
    [[UIApplication sharedApplication]setStatusBarHidden:YES];

}
-(void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    self.tabBarController.tabBar.hidden = NO;
    self.navigationController.navigationBar.hidden= NO;
    [[UIApplication sharedApplication]setStatusBarHidden:NO];

    [self.wkWebView.configuration.userContentController removeScriptMessageHandlerForName:@"WXPay"];
    [self.wkWebView setNavigationDelegate:nil];
    [self.wkWebView setUIDelegate:nil];

    //清除缓存
    [[NSURLCache sharedURLCache] removeCachedResponseForRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:
                                                                                              @"https://www.baidu.com"]]]; }

- (void)viewDidLoad { [super viewDidLoad]; [self CreatUI]; }
-(void)CreatUI{ self.view.backgroundColor = [UIColor blackColor];
    [self.wkWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.baidu.com"]]]; //添加到主控制器上

    [self.view addSubview:self.wkWebView];
    //添加进度条
    [self.view addSubview:self.progressView];
//
//    back = [myButton buttonWithType:UIButtonTypeCustom frame:CGRectMake(ScreenWidth-IPHONEWIDTH(120), ScreenHeight-IPHONEHIGHT(100), IPHONEWIDTH(50), IPHONEHIGHT(50)) tag:1 image:@"ic_history_ct_return" andBlock:^(myButton *button) {
//
//        [self.navigationController popViewControllerAnimated:YES];
//
//
//    }];
//
//    [self.view addSubview:back];
//    

        labeltitle = [[UILabel alloc] initWithFrame:CGRectMake(, IPHONEHIGHT(), self.view.bounds.size.width, IPHONEHIGHT())];
        //设置成绿色
        labeltitle.backgroundColor = [UIColor blackColor];
        labeltitle.text =@"Title";

        labeltitle.textColor = [UIColor whiteColor];
        labeltitle.font = [UIFont boldSystemFontOfSize:IPHONEHIGHT()];
        labeltitle.textAlignment = NSTextAlignmentCenter;

        [self.view addSubview:labeltitle];

//    [MBProgressHUD showHUDAddedTo:self.view animated:YES];

}

#pragma mark ================ WKNavigationDelegate ================

//这个是网页加载完成，导航的变化
-(void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation{
        [labeltitle removeFromSuperview];
//    [MBProgressHUD hideHUDForView:self.view animated:YES];
    [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];

}

//开始加载
-(void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation{
    //开始加载的时候，让加载进度条显示
    self.progressView.hidden = NO;

}

//内容返回时调用
-(void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation{}

//服务器请求跳转的时候调用
-(void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation{}

// 内容加载失败时候调用
-(void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation withError:(NSError *)error{
    NSLog(@"页面加载超时");
//    [MBProgressHUD hideHUDForView:self.view animated:YES];

//    [MBProgressHUD showText:@"加载失败，请重试" HUDAddedTo:self.view animated:YES afterDelay:1.5];
}

//跳转失败的时候调用
-(void)webView:(WKWebView *)webView didFailNavigation:(WKNavigation *)navigation withError:(NSError *)error{}

//进度条
-(void)webViewWebContentProcessDidTerminate:(WKWebView *)webView{}

//KVO监听进度条
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {

    if ([keyPath isEqualToString:NSStringFromSelector(@selector(estimatedProgress))] && object == self.wkWebView) {
        [self.progressView setAlpha:1.0f];
        BOOL animated = self.wkWebView.estimatedProgress > self.progressView.progress;
        [self.progressView setProgress:self.wkWebView.estimatedProgress animated:animated];

        // Once complete, fade out UIProgressView
        if(self.wkWebView.estimatedProgress >= 1.0f) {
            [UIView animateWithDuration:0.3f delay:0.3f options:UIViewAnimationOptionCurveEaseOut animations:^{
                [self.progressView setAlpha:0.0f];
            } completion:^(BOOL finished) {
                [self.progressView setProgress:0.0f animated:NO];
            }];
        }
    }
    else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

#pragma mark ================ 懒加载 ================

- (WKWebView *)wkWebView{
    if (!_wkWebView) {
        //设置网页的配置文件
        WKWebViewConfiguration * Configuration = [[WKWebViewConfiguration alloc]init];
        //允许视频播放
        Configuration.allowsAirPlayForMediaPlayback = YES;
        // 允许在线播放
        Configuration.allowsInlineMediaPlayback = YES;
        // 允许可以与网页交互，选择视图
        Configuration.selectionGranularity = YES;
        // web内容处理池
        Configuration.processPool = [[WKProcessPool alloc] init];
        //自定义配置,一般用于 js调用oc方法(OC拦截URL中的数据做自定义操作)
        WKUserContentController * UserContentController = [[WKUserContentController alloc]init];
        // 添加消息处理，注意：self指代的对象需要遵守WKScriptMessageHandler协议，结束时需要移除
        [UserContentController addScriptMessageHandler:self name:@"WXPay"];
        // 是否支持记忆读取
        Configuration.suppressesIncrementalRendering = YES;
        // 允许用户更改网页的设置
        Configuration.userContentController = UserContentController;
        _wkWebView = [[WKWebView alloc] initWithFrame:self.view.bounds configuration:Configuration];
        _wkWebView.backgroundColor = [UIColor blackColor];
        // 设置代理
        _wkWebView.navigationDelegate = self;
        _wkWebView.UIDelegate = self;
        //kvo 添加进度监控
        [_wkWebView addObserver:self forKeyPath:NSStringFromSelector(@selector(estimatedProgress)) options: context:WkwebBrowserContext];
        //开启手势触摸
        _wkWebView.allowsBackForwardNavigationGestures = YES;
        // 设置 可以前进 和 后退
        //适应你设定的尺寸
        [_wkWebView sizeToFit];
    }
    return _wkWebView;
}

- (UIProgressView *)progressView{
    if (!_progressView) {
        _progressView = [[UIProgressView alloc]initWithProgressViewStyle:UIProgressViewStyleDefault];

        _progressView.frame = CGRectMake(, IPHONEHIGHT(), self.view.bounds.size.width, IPHONEHIGHT());

        // 设置进度条的色彩
        [_progressView setTrackTintColor:[UIColor colorWithRed:240.0/ green:240.0/ blue:240.0/ alpha:1.0]];
        _progressView.progressTintColor = [UIColor greenColor];
    }
    return _progressView;
}

//注意，观察的移除
-(void)dealloc{
    [self.wkWebView removeObserver:self forKeyPath:NSStringFromSelector(@selector(estimatedProgress))];
}

@end

不建议采用下方代码，会在网络缓慢时有白屏现象

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1/拖到自己的