iOS開發之WKWebView代替UIWebView

Xcode8發佈以後，編譯器開始不支持IOS7，所以很多應用在適配IOS10之後都不在適配IOS7了，其中包括了很多大公司，網易新聞，滴滴出行等。因此，我們公司的應用也打算淘汰IOS7。
支持到IOS8，第一個要改的自然是用WKWebView替換原來的UIWebView。WKWebView有很多明顯優勢:

1,更多的支持HTML5的特性

2,官方宣稱的高達60fps的滾動刷新率以及內置手勢

3,將UIWebViewDelegate與UIWebView拆分成了14類與3個協議,以前很多不方便實現的功能得以實現。官方文檔

4,Safari相同的JavaScript引擎

5,佔用更少的內存

UIWebView

WKWebView

基本使用方法

WKWebView有兩個delegate,WKUIDelegate 和 WKNavigationDelegate。WKNavigationDelegate主要處理一些跳轉、加載處理操作，WKUIDelegate主要處理JS腳本，確認框，警告框等。因此WKNavigationDelegate更加常用。
比較常用的方法：

#pragma mark - lifeCircle
- (void)viewDidLoad {
    [super viewDidLoad];
    webView = [[WKWebView alloc]init];
    [self.view addSubview:webView];
    [webView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.equalTo(self.view);
        make.right.equalTo(self.view);
        make.top.equalTo(self.view);
        make.bottom.equalTo(self.view);
    }];
    webView.UIDelegate = self;
    webView.navigationDelegate = self;
    [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.baidu.com"]]];

}

#pragma mark - WKNavigationDelegate
// 頁面開始加載時調用
- (void)webView:(WKWebView *)webView didStartProvisionalNavigation:(WKNavigation *)navigation{

}
// 當內容開始返回時調用
- (void)webView:(WKWebView *)webView didCommitNavigation:(WKNavigation *)navigation{

}
// 頁面加載完成之後調用
- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation{

}
// 頁面加載失敗時調用
- (void)webView:(WKWebView *)webView didFailProvisionalNavigation:(WKNavigation *)navigation{

}
// 接收到服務器跳轉請求之後調用
- (void)webView:(WKWebView *)webView didReceiveServerRedirectForProvisionalNavigation:(WKNavigation *)navigation{

}
// 在收到響應後，決定是否跳轉
- (void)webView:(WKWebView *)webView decidePolicyForNavigationResponse:(WKNavigationResponse *)navigationResponse decisionHandler:(void (^)(WKNavigationResponsePolicy))decisionHandler{

    NSLog(@"%@",navigationResponse.response.URL.absoluteString);
    //允許跳轉
    decisionHandler(WKNavigationResponsePolicyAllow);
    //不允許跳轉
    //decisionHandler(WKNavigationResponsePolicyCancel);
}
// 在發送請求之前，決定是否跳轉
- (void)webView:(WKWebView *)webView decidePolicyForNavigationAction:(WKNavigationAction *)navigationAction decisionHandler:(void (^)(WKNavigationActionPolicy))decisionHandler{

     NSLog(@"%@",navigationAction.request.URL.absoluteString);
    //允許跳轉
    decisionHandler(WKNavigationActionPolicyAllow);
    //不允許跳轉
    //decisionHandler(WKNavigationActionPolicyCancel);
}

#pragma mark - WKUIDelegate
// 創建一個新的WebView
- (WKWebView *)webView:(WKWebView *)webView createWebViewWithConfiguration:(WKWebViewConfiguration *)configuration forNavigationAction:(WKNavigationAction *)navigationAction windowFeatures:(WKWindowFeatures *)windowFeatures{
    return [[WKWebView alloc]init];
}
// 輸入框
- (void)webView:(WKWebView *)webView runJavaScriptTextInputPanelWithPrompt:(NSString *)prompt defaultText:(nullable NSString *)defaultText initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(NSString * __nullable result))completionHandler{
    completionHandler(@"http");
}
// 確認框
- (void)webView:(WKWebView *)webView runJavaScriptConfirmPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(BOOL result))completionHandler{
    completionHandler(YES);
}
// 警告框
- (void)webView:(WKWebView *)webView runJavaScriptAlertPanelWithMessage:(NSString *)message initiatedByFrame:(WKFrameInfo *)frame completionHandler:(void (^)(void))completionHandler{
    NSLog(@"%@",message);
    completionHandler();
}

OC與JS交互
WKWebview提供了API實現js交互不需要藉助JavaScriptCore或者webJavaScriptBridge。使用WKUserContentController實現js native交互。簡單的說就是先註冊約定好的方法，然後再調用。
JS調用OC方法
oc代碼(有誤，內存不釋放):

@interface ViewController ()<WKUIDelegate,WKNavigationDelegate,WKScriptMessageHandler>{
    WKWebView * webView;
    WKUserContentController* userContentController;
}
@end

@implementation ViewController
#pragma mark - lifeCircle
- (void)viewDidLoad {
    [super viewDidLoad];
    //配置環境
    WKWebViewConfiguration * configuration = [[WKWebViewConfiguration alloc]init];
    userContentController =[[WKUserContentController alloc]init];
    configuration.userContentController = userContentController;
    webView = [[WKWebView alloc]initWithFrame:CGRectMake(0, 0, 100, 100) configuration:configuration];
    //註冊方法
    [userContentController addScriptMessageHandler:self  name:@"sayhello"];//註冊一個name爲sayhello的js方法

    [self.view addSubview:webView];
    [webView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.equalTo(self.view);
        make.right.equalTo(self.view);
        make.top.equalTo(self.view);
        make.bottom.equalTo(self.view);
    }];
    webView.UIDelegate = self;
    webView.navigationDelegate = self;
    [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.test.com"]]];
}
- (void)dealloc{
    //這裏需要注意，前面增加過的方法一定要remove掉。
    [userContentController removeScriptMessageHandlerForName:@"sayhello"];
}

#pragma mark - WKScriptMessageHandler
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
    NSLog(@"name:%@\\\\n body:%@\\\\n frameInfo:%@\\\\n",message.name,message.body,message.frameInfo);
}
@end

上面的OC代碼如果認證測試一下就會發現dealloc並不會執行，這樣肯定是不行的，會造成內存泄漏。原因是[userContentController addScriptMessageHandler:self name:@”sayhello”];這句代碼造成無法釋放內存。（ps:試了下用weak指針還是不能釋放，不知道是什麼原因。）因此還需要進一步改進，正確的寫法是用一個新的controller來處理,新的controller再繞用delegate繞回來。
oc代碼(正確寫法):

@interface ViewController ()<WKUIDelegate,WKNavigationDelegate,WKScriptMessageHandler>{
    WKWebView * webView;
    WKUserContentController* userContentController;
}
@end

@implementation ViewController
#pragma mark - lifeCircle
- (void)viewDidLoad {
    [super viewDidLoad];
    //配置環境
    WKWebViewConfiguration * configuration = [[WKWebViewConfiguration alloc]init];
    userContentController =[[WKUserContentController alloc]init];
    configuration.userContentController = userContentController;
    webView = [[WKWebView alloc]initWithFrame:CGRectMake(0, 0, 100, 100) configuration:configuration];
    //註冊方法
    WKDelegateController * delegateController = [[WKDelegateController alloc]init];
    delegateController.delegate = self;

    [userContentController addScriptMessageHandler:delegateController  name:@"sayhello"];

    [self.view addSubview:webView];
    [webView mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.equalTo(self.view);
        make.right.equalTo(self.view);
        make.top.equalTo(self.view);
        make.bottom.equalTo(self.view);
    }];
    webView.UIDelegate = self;
    webView.navigationDelegate = self;
    [webView loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.test.com"]]];
}
- (void)dealloc{
    //這裏需要注意，前面增加過的方法一定要remove掉。
    [userContentController removeScriptMessageHandlerForName:@"sayhello"];
}

#pragma mark - WKScriptMessageHandler
- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
    NSLog(@"name:%@\\\\n body:%@\\\\n frameInfo:%@\\\\n",message.name,message.body,message.frameInfo);
}
@end

WKDelegateController代碼：

#import <UIKit/UIKit.h>
#import <WebKit/WebKit.h>
@protocol WKDelegate <NSObject>

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message;

@end

@interface WKDelegateController : UIViewController <WKScriptMessageHandler>

@property (weak , nonatomic) id<WKDelegate> delegate;

@end

.m代碼：

#import "WKDelegateController.h"

@interface WKDelegateController ()

@end

@implementation WKDelegateController

- (void)viewDidLoad {
    [super viewDidLoad];
}

- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message{
    if ([self.delegate respondsToSelector:@selector(userContentController:didReceiveScriptMessage:)]) {
        [self.delegate userContentController:userContentController didReceiveScriptMessage:message];
    }
}


@end

h5代碼:

<html>
<head>
    <script>
function say()
{
//前端需要用 window.webkit.messageHandlers.註冊的方法名.postMessage({body:傳輸的數據} 來給native發送消息
    window.webkit.messageHandlers.sayhello.postMessage({body: 'hello world!'});
}
</script>
</head>
    <body>
        <h1>hello world</h1>
        <button onclick="say()">say hello</button>
    </body>

</html>

打印出的log：

 name:sayhello
 body:{
    body = "hello world!";
}
 frameInfo:<WKFrameInfo: 0x7f872060ce20; isMainFrame = YES; request =     <NSMutableURLRequest: 0x618000010a30> { URL: http://www.test.com/ }>

注意點

addScriptMessageHandler要和removeScriptMessageHandlerForName配套出現，否則會造成內存泄漏。
h5只能傳一個參數，如果需要多個參數就需要用字典或者json組裝。
oc調用JS方法
代碼如下：

- (void)webView:(WKWebView *)tmpWebView didFinishNavigation:(WKNavigation *)navigation{

    //say()是JS方法名，completionHandler是異步回調block
    [webView evaluateJavaScript:@"say()" completionHandler:^(id _Nullable result, NSError * _Nullable error) {
        NSLog(@"%@",result);
    }];

}

h5代碼同上。
WebViewJavascriptBridge
一般來說，一個好的UI總有一個大神會開發出一個好的第三方封裝框架。WebViewJavascriptBridge的作者也做了一套支持WKWebView與JS交互的第三方框架:WKWebViewJavascriptBridge。
cocoaPods: pod ‘WebViewJavascriptBridge’, ‘~> 5.0.5’
github地址：https://github.com/marcuswestin/WebViewJavascriptBridge
主要方法如下：

//初始化方法
+ (instancetype)bridgeForWebView:(WKWebView*)webView;
+ (void)enableLogging;

//註冊函數名
- (void)registerHandler:(NSString*)handlerName handler:(WVJBHandler)handler;

//調用函數名
- (void)callHandler:(NSString*)handlerName;
- (void)callHandler:(NSString*)handlerName data:(id)data;
- (void)callHandler:(NSString*)handlerName data:(id)data responseCallback:(WVJBResponseCallback)responseCallback;

//重置
- (void)reset;

//設置WKNavigationDelegate
- (void)setWebViewDelegate:(id<WKNavigationDelegate>)webViewDelegate;

基本的實現方法和上面寫的差不多，就是封裝了一下，有興趣的童鞋可以自己pod下來使用。

iOS開發之WKWebView代替UIWebView

1,更多的支持HTML5的特性

2,官方宣稱的高達60fps的滾動刷新率以及內置手勢

3,將UIWebViewDelegate與UIWebView拆分成了14類與3個協議,以前很多不方便實現的功能得以實現。官方文檔

4,Safari相同的JavaScript引擎

5,佔用更少的內存

UIWebView

基本使用方法

注意點

GCD高級功能(一次性執行,調度組,延遲操作)

AFN應用及原理

NSCache的簡單介紹應用

IOS 本地和遠程推送通知詳解

iOS 遠程推送通知

https://yachay.unat.edu.pe/blog/index.php?comment_area=format_blog&comment_component=blog&comment_co

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