使用到的第三方库：NJKWebViewProgress

使用：采用代理方式，在代理中获取进度，并赋值给进度条。具体看代码。

#import "ViewController.h"
#import "NJKWebViewProgress.h"
#import "NJKWebViewProgressView.h"

@interface ViewController ()<UIWebViewDelegate,NJKWebViewProgressDelegate>

@property (nonatomic, strong) UIView *maskView;
@property (nonatomic, strong) UIView *urlInputView;
@property (nonatomic, strong) UITextField *urlInput;
@property (nonatomic, strong) UIWebView *webView;
@property (nonatomic, strong) NJKWebViewProgressView *progressView;
@property (nonatomic, strong) NJKWebViewProgress *progressProxy;

@end

@implementation ViewController

- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    
    // 添加进度条
    [self.navigationController.navigationBar addSubview:self.progressView];
}

-(void)viewWillDisappear:(BOOL)animated{
    [super viewWillDisappear:animated];
    
    // 因为与其他viewcontroller共用一个UINavigationBar，所以需要移除进度条
    [self.progressView removeFromSuperview];
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.title = @"Test_WebViewProgress";
    self.navigationController.navigationBar.translucent = NO;
    
    self.webView = [[UIWebView alloc] initWithFrame:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height - 64)];
    [self.view addSubview:self.webView];
    
    NSString *url = @"http://www.jianshu.com/u/b05772019513";
    [[NSUserDefaults standardUserDefaults] setObject:url forKey:@"weburl"];
    
    [self loadWithUrlStr:url];
}

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

#pragma mark -- NJKWebViewProgressDelegate
- (void)webViewProgress:(NJKWebViewProgress *)webViewProgress updateProgress:(float)progress{
    
    [self.progressView setProgress:progress animated:YES];
    
    self.title = [self.webView stringByEvaluatingJavaScriptFromString:@"document.title"];
}

/** 重新加载*/
- (IBAction)reload:(id)sender {
    [self.webView reload];
}

/** 打开 url 输入面板*/
- (IBAction)onOpenUrlInput:(id)sender{
    
    if (self.maskView == nil) {
        self.maskView = [[UIView alloc]initWithFrame:[UIScreen mainScreen].bounds];
        self.maskView.backgroundColor = [UIColor colorWithRed:0.0 green:0.0 blue:0.0 alpha:0.75];
    }
    
    if (self.urlInputView == nil) {
        self.urlInputView = [[UIView alloc]initWithFrame:CGRectMake(0, 0, 300, 105)];
        self.urlInputView.backgroundColor = [UIColor lightGrayColor];
        self.urlInputView.layer.cornerRadius = 8.0f;
        self.urlInputView.layer.masksToBounds = YES;
        
        self.urlInput = [[UITextField alloc]initWithFrame:CGRectMake(10, 15, 280, 30)];
        self.urlInput.autocapitalizationType = UITextAutocapitalizationTypeNone;
        self.urlInput.autocorrectionType = UITextAutocorrectionTypeNo;
        self.urlInput.clearButtonMode = UITextFieldViewModeWhileEditing;
        self.urlInput.backgroundColor = [UIColor whiteColor];
        self.urlInput.layer.cornerRadius = 4.0f;
        self.urlInput.layer.masksToBounds = YES;
        [self.urlInputView addSubview:self.urlInput];
        
        UIButton* btn = [[UIButton alloc]initWithFrame:CGRectMake(230, 60, 60, 30)];
        btn.backgroundColor = [UIColor colorWithRed:81.0f/255.0f green:141.0f/255.0f blue:229.0f/255.0f alpha:1.0f];
        btn.layer.cornerRadius = 4.0f;
        btn.layer.masksToBounds = YES;
        
        [btn setTitle:@"Load" forState:UIControlStateNormal];
        [btn addTarget:self action:@selector(onOpenInputedUrl:) forControlEvents:UIControlEventTouchUpInside];
        [self.urlInputView addSubview:btn];
    }
    
    NSString* webUrl = [[NSUserDefaults standardUserDefaults]objectForKey:@"weburl"];
    self.urlInput.text = webUrl;
    
    UIWindow* keyWnd = [UIApplication sharedApplication].keyWindow;
    if (keyWnd) {
        if (self.maskView.superview) {
            [self.maskView removeFromSuperview];
        }
        [keyWnd addSubview:self.maskView];
        
        if (self.urlInputView.superview) {
            [self.urlInputView removeFromSuperview];
        }
        [keyWnd addSubview:self.urlInputView];
        self.urlInputView.center = keyWnd.center;
        CGRect frame = self.urlInputView.frame;
        frame.origin.y = 84;
        self.urlInputView.frame = frame;
    }
}

/** 点击 load 按钮 */
- (void)onOpenInputedUrl:(id)sender{
    
    if (self.urlInputView.superview) {
        [self.urlInputView removeFromSuperview];
    }
    
    if (self.maskView.superview) {
        [self.maskView removeFromSuperview];
    }
    
    NSString* urlStr = self.urlInput.text;
    if (urlStr.length > 0) {
        if (![urlStr hasPrefix:@"http"]) {
            urlStr = [NSString stringWithFormat:@"http://%@", urlStr];
        }
        [[NSUserDefaults standardUserDefaults] setObject:urlStr forKey:@"weburl"];
        [self loadWithUrlStr:urlStr];
    }
}

/** 导航条下面的进度条 */
- (NJKWebViewProgressView *)progressView {
    if(!_progressView) {
        _progressProxy = [[NJKWebViewProgress alloc] init];
        _webView.delegate = _progressProxy;
        _progressProxy.webViewProxyDelegate = self;
        _progressProxy.progressDelegate = self;
        
        CGFloat progressBarHeight = 2.f;
        CGRect navigaitonBarBounds = self.navigationController.navigationBar.bounds;
        CGRect barFrame = CGRectMake(0, navigaitonBarBounds.size.height - progressBarHeight, navigaitonBarBounds.size.width, progressBarHeight);
        _progressView = [[NJKWebViewProgressView alloc] initWithFrame:barFrame];
        _progressView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleTopMargin;
        _progressView.progressBarView.backgroundColor = [UIColor blueColor];
        _progressView.progress = 0;
    }
    return _progressView;
}

/**加载 url */
- (void)loadWithUrlStr:(NSString*)urlStr{
    
    if (urlStr.length > 0) {
        dispatch_async(dispatch_get_main_queue(), ^{
            NSURLRequest *webRequest = [NSURLRequest requestWithURL:[NSURL URLWithString:urlStr]
                                                        cachePolicy:NSURLRequestReturnCacheDataElseLoad
                                                    timeoutInterval:30];
            [self.webView loadRequest:webRequest];
        });
    }
}

@end

运行效果：

运行效果

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