WkWebView进度条

WKWebView有一个属性estimatedProgress，就是当前网页加载的进度，所以首先监听这个属性。

WKWebView *webView = [[WKWebView alloc]initWithFrame:[UIScreen mainScreen].bounds];
[webView addObserver:self forKeyPath:@"estimatedProgress" options:NSKeyValueObservingOptionNew context:nil];

接下来，就是弄一个进度条啦，在viewDidLoad方法里面写：

    UIView *progress = [[UIView alloc]initWithFrame:CGRectMake(0, 64, CGRectGetWidth(self.view.frame), 3)];
    progress.backgroundColor = [UIColor clearColor];
    [self.view addSubview:progress];

    CALayer *layer = [CALayer layer];
    layer.frame = CGRectMake(0, 0, 0, 3);
    layer.backgroundColor = COLOR_BAR_TIN.CGColor;
    [progress.layer addSublayer:layer];
    self.progresslayer = layer;

为什么要用CALayer？隐式动画啊。然后就是监听方法啦

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context{ if ([keyPath isEqualToString:@"estimatedProgress"]) { self.progresslayer.opacity = 1;
        //不要让进度条倒着走...有时候goback会出现这种情况
        if ([change[@"new"] floatValue] < [change[@"old"] floatValue]) { return;
        }
        self.progresslayer.frame = CGRectMake(0, 0, self.view.bounds.size.width * [change[@"new"] floatValue], 3);
        if ([change[@"new"] floatValue] == 1) { dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(.4 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{ self.progresslayer.opacity = 0;
            });
            dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
                self.progresslayer.frame = CGRectMake(0, 0, 0, 3);
            });
        }
    }else{
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}

拷贝到自己的项目里面就OK啦，是不是很爽呢？最后别忘了取消监听...

- (void)dealloc{
    [(WKWebView *)self.view removeObserver:self forKeyPath:@"estimatedProgress"];
}

文／飞烟灰灭（简书作者）
原文链接：http://www.jianshu.com/p/24b3e3ddc946
著作权归作者所有，转载请联系作者获得授权，并标注“简书作者”。