原作者github链接:https://github.com/ninjinkun/NJKWebViewProgress
效果如下图:

NJKWebViewProgress.gif

#import <UIKit/UIKit.h>
#import "NJKWebViewProgress.h"
#import "NJKWebViewProgressView.h"
@interface ViewController : UIViewController<UIWebViewDelegate, NJKWebViewProgressDelegate>
@end

#import "ViewController.h"

@interface ViewController ()
@property (nonatomic, strong) UIWebView *webV;
@end

@implementation ViewController
{
    NJKWebViewProgressView *_progressView;
    NJKWebViewProgress *_progressProxy;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    self.title = @"商城";
//关闭NavgationBar的自适应64高度
    self.automaticallyAdjustsScrollViewInsets = NO;
//初始化webView
   self.webV = [[UIWebView alloc] initWithFrame:CGRectMake(0, 64, [UIScreen mainScreen].bounds.size.width, [UIScreen mainScreen].bounds.size.height - 64)];
    [self.view addSubview:_webV];
//初始化进度条
    _progressProxy = [[NJKWebViewProgress alloc] init];
    _webV.delegate = _progressProxy;
    _progressProxy.webViewProxyDelegate = self;
    _progressProxy.progressDelegate = self;
//进度条高度
    CGFloat progressBarHeight = 2.f;
    CGRect navigationBarBounds = self.navigationController.navigationBar.bounds;
//进度条的frame
    CGRect barFrame = CGRectMake(0, navigationBarBounds.size.height - progressBarHeight, navigationBarBounds.size.width, progressBarHeight);
    _progressView = [[NJKWebViewProgressView alloc] initWithFrame:barFrame];
//设置进度条颜色
   _progressView.progressBarView.backgroundColor = [UIColor redColor];
    _progressView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleTopMargin;
   [_progressView setProgress:0 animated:YES];
//开始请求网络
    NSURLRequest *req = [[NSURLRequest alloc] initWithURL:[NSURL URLWithString:@"www.baidu.com"]];
    [self.webV loadRequest:req];

}

#pragma mark - NJKWebViewProgressDelegate
- (void)webViewProgress:(NJKWebViewProgress *)webViewProgress updateProgress:(float)progress{
    [_progressView setProgress:progress animated:YES];
}

- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    [self.navigationController.navigationBar addSubview:_progressView];
}
-(void)viewWillDisappear:(BOOL)animated
{
    [super viewWillDisappear:animated];
    [_progressView removeFromSuperview];
}