#import "ViewController.h"
#include <WebKit/WebKit.h>
@interface ViewController ()
@property(nonatomic,strong)WKWebView *testWebView;
@property(nonatomic,strong)UIProgressView *progressView;
@end
// 屏幕高度
#define SCREEN_HEIGHT         [[UIScreen mainScreen] bounds].size.height
// 屏幕宽度
#define SCREEN_WIDTH          [[UIScreen mainScreen] bounds].size.width

@implementation ViewController

- (void)viewDidLoad {
[super viewDidLoad];
// 初始化 wkwebView
_testWebView = [[WKWebView alloc]init];
_testWebView.frame = CGRectMake(0, 20, SCREEN_WIDTH, SCREEN_HEIGHT);
[self.view addSubview:_testWebView];

// 设置进度条
_progressView = [[UIProgressView alloc]init];
_progressView.frame = CGRectMake(0, 20, SCREEN_WIDTH, 5);
_progressView.backgroundColor = [UIColor greenColor];
[self.view addSubview:_progressView];
// 添加监测
[_testWebView addObserver:self forKeyPath:@"estimatedProgress" options:NSKeyValueObservingOptionNew| NSKeyValueObservingOptionOld context:nil];
[_testWebView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"https://www.baidu.com"]]];


// Do any additional setup after loading the view, typically from a nib.
}
// 实现监测
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context{
NSLog(@" %s,change = %@",__FUNCTION__,change);
if ([keyPath isEqual: @"estimatedProgress"] && object == _testWebView) {
    [self.progressView setAlpha:1.0f];
    [self.progressView setProgress:_testWebView.estimatedProgress animated:YES];
    if(_testWebView.estimatedProgress >= 1.0f)
    {
        [UIView animateWithDuration:0.3 delay:0.3 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 {
[_testWebView removeObserver:self forKeyPath:@"estimatedProgress"];
// if you have set either WKWebView delegate also set these to nil here
[_testWebView setNavigationDelegate:nil];
[_testWebView setUIDelegate:nil];
}