1、前言

iOS8後，蘋果推出了新框架Webkit，提供了替換UIWebView的元件WKWebView，相比於UIWebView,好處多多，速度更快了，佔用記憶體少了。

2、基本使用

使用方法和UIWebView大同小異，具體使用可以參考使用WKWebView替換UIWebView,這篇文章講的挺詳細了，這不是我們本篇的重點，我們的重點是講下怎麼頁面title和載入進度值。

注意：使用時記得匯入WebKit.framework框架

3、獲得頁面title和載入進度值(基於系統KVO)

//匯入框架
#import <WebKit/WebKit.h>
/*********/
 

@property (nonatomic, strong) WKWebView *mWebView;//webView
@property (nonatomic, strong) UIProgressView *mProgressView;//進度條
/*********/
- (void)viewDidLoad {
  [super viewDidLoad];
  [self initWebView];
}
  //增加kvo監聽，獲得頁面title和載入進度值
- (void)viewWillAppear:(BOOL)animated{
    [super viewWillAppear:animated];
    [self
 
.mWebView addObserver:self forKeyPath:@"estimatedProgress" options:NSKeyValueObservingOptionNew context:NULL];
    [self.mWebView addObserver:self forKeyPath:@"title" options:NSKeyValueObservingOptionNew context:NULL];
}
//KVO 一定要移除，要不然會崩潰
- (void)dealloc{
    [self.mWebView removeObserver:self forKeyPath:@"estimatedProgress"
 
];
    [self.mWebView removeObserver:self forKeyPath:@"title"];
}

- (void)initWebView
{
    _mWebView = [[WKWebView alloc] initWithFrame:CGRectMake(0, 0, ScreenWidth, ScreenHeight - TopFullHeight)];
    [_mWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http:xxxxx"]]];
    [self.view addSubview:_mWebView];

    //進度條新增到navigationBar
    CGFloat progressBarHeight = 2.0f;
    CGRect navigationBarBounds = self.navigationController.navigationBar.bounds;
    CGRect barFrame = CGRectMake(0, navigationBarBounds.size.height - progressBarHeight, navigationBarBounds.size.width, progressBarHeight);
    _mProgressView = [[UIProgressView alloc] initWithFrame:barFrame];
    _mProgressView.autoresizingMask = UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleTopMargin;
    _mProgressView.progressTintColor = [UIColor greenColor];
    [self.navigationController.navigationBar addSubview:_mProgressView];
}

#pragma mark KVO的監聽代理
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {

    //載入進度值
    if ([keyPath isEqualToString:@"estimatedProgress"]){
        if (object == self.mWebView){
            self.mProgressView.alpha = 1;
            [self.mProgressView setProgress:self.mWebView.estimatedProgress animated:YES];
            if(self.mWebView.estimatedProgress >= 1.0f)
            {
                [UIView animateWithDuration:0.5 animations:^{
                    self.mProgressView.alpha = 0;
                } completion:^(BOOL finished) {
                     [self.mProgressView setProgress:0.0f animated:NO];
                }];
            }
        }else{
            [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
        }
    }else if ([keyPath isEqualToString:@"title"]){//網頁title
        if (object == self.mWebView){
            self.navigationItem.title = self.mWebView.title;
        }else{
            [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
        }
    }else{
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

至此，載入標題和進度值完成，try。

KVOController是facebook開源的一個KVO框架，使用方便，好處多多，我就是因為側滑返回偶爾導致系統KVO沒有釋放，最後程式崩潰了，所以這裡建議使用這個框架，使用程式碼入下

#import "FBKVOController.h"
@property (nonatomic, strong) FBKVOController *kvoController;

- (void)initFBKVO{

    //KVO
    __weak typeof (self) weakSelf = self;
    self.kvoController = [FBKVOController controllerWithObserver:self];
    [self.kvoController observe:self.mWebView keyPath:@"estimatedProgress" options:NSKeyValueObservingOptionNew block:^(id  _Nullable observer, id  _Nonnull object, NSDictionary<NSString *,id> * _Nonnull change) {

        weakSelf.mProgressView.alpha = 1;
        [weakSelf.mProgressView setProgress:self.mWebView.estimatedProgress animated:YES];
        if(weakSelf.mWebView.estimatedProgress >= 1.0f)
        {
            [UIView animateWithDuration:0.5 animations:^{
                weakSelf.mProgressView.alpha = 0;
            } completion:^(BOOL finished) {
                [weakSelf.mProgressView setProgress:0.0f animated:NO];
            }];
        }  
    }];

    [self.kvoController observe:self.mWebView keyPath:@"title" options:NSKeyValueObservingOptionNew block:^(id  _Nullable observer, id  _Nonnull object, NSDictionary<NSString *,id> * _Nonnull change) {
         weakSelf.navigationItem.title = self.mWebView.title;
    }];
}

參考