WebView、网络操作相关及键盘相关的几个关键类

UIWebview的本地调用

注入js:[webview stringByEvaluatingJavaScriptFromString:]
本地调用，使用WebViewJavascriptBridge：- (void)registerHandler:(NSString *)handlerName handler:(WVJBHandler)handler

WKWebView的本地调用

注入js:[wkwebview evaluateJavaScript:]
首先通过WKUserContentController -> addScriptMessageHandler: 以及 addUserScript: ,实现WKScriptMessageHandler响应脚本消息:- (void)userContentController:(WKUserContentController *)userContentController didReceiveScriptMessage:(WKScriptMessage *)message 和 js的注入；
WKNavigationDelegate：跟踪网页加载进度，以及决定采取什么的处理策略；
WKUIDelegate:根据网页的行为展示本地的UI视图；

自定义NSURLProtocol

NSURLProtocol能够让你去重新定义苹果的URL加载系统 (URL Loading System)的行为，URL Loading System里有许多类用于处理URL请求，比如NSURL，NSURLRequest，NSURLConnection和NSURLSession等，当URL Loading System使用NSURLRequest去获取资源的时候，它会创建一个NSURLProtocol子类的实例，你不应该直接实例化一个NSURLProtocol，NSURLProtocol看起来像是一个协议，但其实这是一个类，而且必须使用该类的子类，并且需要被注册。
不管你是通过UIWebView, NSURLConnection 或者第三方库 (AFNetworking, MKNetworkKit等)，他们都是基于NSURLConnection或者 NSURLSession实现的，因此你可以通过NSURLProtocol做自定义的操作。
- 重定向网络请求
- 忽略网络请求，使用本地缓存
- 自定义网络请求的返回结果
- 一些全局的网络请求设置

子类化NSURLProtocol并注册

//子类化
@interface CustomURLProtocol : NSURLProtocol
@end

//注册
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    //注册protocol
    [NSURLProtocol registerClass:[CustomURLProtocol class]];
    return YES;
}

实现Custom URLProtocol

+canInitWithRequest:这个方法主要是说明你是否打算处理对应的request，如果不打算处理，返回NO，URL Loading System会使用系统默认的行为去处理；如果打算处理，返回YES，然后你就需要处理该请求的所有东西，包括获取请求数据并返回给 URL Loading System。

+ (BOOL)canInitWithRequest:(NSURLRequest *)request
{
  //只处理http和https请求
    NSString *scheme = [[request URL] scheme];
    if ( ([scheme caseInsensitiveCompare:@"http"] == NSOrderedSame ||
     [scheme caseInsensitiveCompare:@"https"] == NSOrderedSame))
    {
        //看看是否已经处理过了，防止无限循环
        if ([NSURLProtocol propertyForKey:URLProtocolHandledKey inRequest:request]) {
            return NO;
        }

        return YES;
    }
    return NO;
}

+canonicalRequestForRequest:通常该方法你可以简单的直接返回request，但也可以在这里修改request，比如添加header，修改host等，并返回一个新的request，这是一个抽象方法，子类必须实现。

+ (NSURLRequest *) canonicalRequestForRequest:(NSURLRequest *)request {
    NSMutableURLRequest *mutableReqeust = [request mutableCopy];
    mutableReqeust = [self redirectHostInRequset:mutableReqeust];
    return mutableReqeust;
}

+(NSMutableURLRequest*)redirectHostInRequset:(NSMutableURLRequest*)request{
    if ([request.URL host].length == 0) {
        return request;
    }

    NSString *originUrlString = [request.URL absoluteString];
    NSString *originHostString = [request.URL host];
    NSRange hostRange = [originUrlString rangeOfString:originHostString];
    if (hostRange.location == NSNotFound) {
        return request;
    }
    //定向到bing搜索主页
    NSString *ip = @"cn.bing.com";

    // 替换域名
    NSString *urlString = [originUrlString stringByReplacingCharactersInRange:hostRange withString:ip];
    NSURL *url = [NSURL URLWithString:urlString];
    request.URL = url;

    return request;
}

+requestIsCacheEquivalent:toRequest:主要判断两个request是否相同，如果相同的话可以使用缓存数据，通常只需要调用父类的实现。
```
+ (BOOL)requestIsCacheEquivalent:(NSURLRequest *)a toRequest:(NSURLRequest *)b{
    return [super requestIsCacheEquivalent:a toRequest:b];
}
```

-startLoading -stopLoading : 这两个方法主要是开始和取消相应的request，而且需要标示那些已经处理过的request。

- (void)startLoading {
    NSMutableURLRequest *mutableReqeust = [[self request] mutableCopy];
    //标示改request已经处理过了，防止无限循环
    [NSURLProtocol setProperty:@YES forKey:URLProtocolHandledKey inRequest:mutableReqeust];
    self.connection = [NSURLConnection connectionWithRequest:mutableReqeust delegate:self];
}

- (void)stopLoading {
    [self.connection cancel];
}

NSURLConnectionDataDelegate方法,在处理网络请求的时候会调用到该代理方法，我们需要将收到的消息通过client返回给URL Loading System。

- (void) connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response {
    [self.client URLProtocol:self didReceiveResponse:response cacheStoragePolicy:NSURLCacheStorageNotAllowed];
}

- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data{
    [self.client URLProtocol:self didLoadData:data];
}

- (void) connectionDidFinishLoading:(NSURLConnection *)connection {
    [self.client URLProtocolDidFinishLoading:self];
}

- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error {
    [self.client URLProtocol:self didFailWithError:error];
}

自定义键盘 UITextInputDelegate 方法定义

- (void)selectionWillChange:(nullable id <UITextInput>)textInput;
- (void)selectionDidChange:(nullable id <UITextInput>)textInput;
- (void)textWillChange:(nullable id <UITextInput>)textInput;
- (void)textDidChange:(nullable id <UITextInput>)textInput;

自定义键盘UIInputViewController的textDocumentProxy定义

@protocol UITextDocumentProxy <UIKeyInput>
    
@property (nullable, nonatomic, readonly) NSString *documentContextBeforeInput;
@property (nullable, nonatomic, readonly) NSString *documentContextAfterInput;
    
// An app can store UITextInputMode in its document context, when user switches to the document, the host will pass the inputMode as documentInputMode to the UIInputViewController,
// which can switch to the inputMode and set primaryLanguage if it supports it.
@property (nullable, nonatomic, readonly) UITextInputMode *documentInputMode NS_AVAILABLE_IOS(10_0);
    
- (void)adjustTextPositionByCharacterOffset:(NSInteger)offset;
    
@end
    
//-----------------
    
@protocol UIKeyInput <UITextInputTraits>
    
#if UIKIT_DEFINE_AS_PROPERTIES
@property(nonatomic, readonly) BOOL hasText;
#else
- (BOOL)hasText;
#endif
- (void)insertText:(NSString *)text;
- (void)deleteBackward;
    
@end

参考以上：

iOS开发之— NSURLProtocol