WKWebView使用

#import "QLCWebViewController.h"
#import <WebKit/WebKit.h>
@interface QLCWebViewController ()
@property (weak, nonatomic) IBOutlet UIView *contentView;
@property (weak, nonatomic) IBOutlet WKWebView *webView;
@property (weak, nonatomic) IBOutlet UIBarButtonItem *backItem;
@property (weak, nonatomic) IBOutlet UIBarButtonItem *forwardItem;
@property (weak, nonatomic) IBOutlet UIProgressView *progressView;
@end

@implementation QLCWebViewController

- (IBAction)goBack:(id)sender {
    [self.webView goBack];
}
- (IBAction)goForward:(id)sender {
    [self.webView goForward];
}
- (IBAction)reload:(id)sender {
    [self.webView reload];
}

#pragma mark - 生命周期方法
- (void)viewDidLayoutSubviews
{
    [super viewDidLayoutSubviews];

    _webView.frame = self.contentView.bounds;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    // 添加webView
    WKWebView *webView = [[WKWebView alloc] init];
    _webView = webView;
    [self.contentView addSubview:webView];

    // 展示网页
    NSURLRequest *request = [NSURLRequest requestWithURL:_url];
    [webView loadRequest:request];

    // KVO监听属性改变
    /*
        Observer:观察者
        KeyPath:观察webView哪个属性
        options:NSKeyValueObservingOptionNew:观察新值改变

        KVO注意点.一定要记得移除
     */
    [webView addObserver:self forKeyPath:@"canGoBack" options:NSKeyValueObservingOptionNew context:nil];
    [webView addObserver:self forKeyPath:@"canGoForward" options:NSKeyValueObservingOptionNew context:nil];
    [webView addObserver:self forKeyPath:@"title" options:NSKeyValueObservingOptionNew context:nil];

    // 进度条
    [webView addObserver:self forKeyPath:@"estimatedProgress" options:NSKeyValueObservingOptionNew context:nil];

}

// 只要观察对象属性有新值就会调用
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context
{
    self.backItem.enabled = self.webView.canGoBack;
    self.forwardItem.enabled = self.webView.canGoForward;
    self.title = self.webView.title;
    self.progressView.progress = self.webView.estimatedProgress;
    self.progressView.hidden = self.webView.estimatedProgress >= 1;
}

#pragma mark - 对象被销毁
- (void)dealloc
{
    [self.webView removeObserver:self forKeyPath:@"canGoBack"];
    [self.webView removeObserver:self forKeyPath:@"title"];
    [self.webView removeObserver:self forKeyPath:@"canGoForward"];
    [self.webView removeObserver:self forKeyPath:@"estimatedProgress"];
}

@end