iOS中WKWebView仿微信加载进度条

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

-(UIProgressView *)progressView{ if (!_progressView) {  _progressView     = [[UIProgressView alloc]           initWithProgressViewStyle:UIProgressViewStyleDefault];  _progressView.frame    = CGRectMake(0, 64, screen_width, 5);  [_progressView setTrackTintColor:[UIColor colorWithRed:240.0/255               green:240.0/255               blue:240.0/255               alpha:1.0]];  _progressView.progressTintColor = [UIColor greenColor]; } return _progressView;}

 [_mywebView addObserver:self      forKeyPath:NSStringFromSelector(@selector(estimatedProgress))      options:0      context:nil];

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

//kvo 监听进度-(void)observeValueForKeyPath:(NSString *)keyPath      ofObject:(id)object      change:(NSDictionary<NSKeyValueChangeKey,id> *)change      context:(void *)context{ if ([keyPath isEqualToString:NSStringFromSelector(@selector(estimatedProgress))]  && object == self.mywebView) {  [self.progressView setAlpha:1.0f];  BOOL animated = self.mywebView.estimatedProgress > self.progressView.progress;  [self.progressView setProgress:self.mywebView.estimatedProgress        animated:animated];  if (self.mywebView.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]; }}

-(void)dealloc{ [self.mywebView removeObserver:self      forKeyPath:NSStringFromSelector(@selector(estimatedProgress))];}