WKWebView POST请求

这一文章介绍如何通过类目让WKWebView优雅的实现POST请求，为啥说是优雅:

实现POST请求

实现原理是通过一段js函数post表单参数，灵感来源于网上（加载一个带有js函数的空页面，页面加载完成后立刻调用函数发起post请求），使用起来貌似需要在代理里边各种穿插代码，我是觉得使用起来不是很方便。
这里实现主要是采用js交互和runtime结合实现，demo：https://github.com/youlianchun/WKWebView_POST
采用swizzledMethod拦截 -[WKWebView loadRequest:],在理面判断POST Request，然后直接拼接执行js代码块

+ (void)load {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Class class = [self class];
        SEL originalSelector = @selector(loadRequest:);
        SEL swizzledSelector = @selector(post_loadRequest:);
        Method originalMethod = class_getInstanceMethod(class, originalSelector);
        Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
        BOOL success = class_addMethod(class, originalSelector, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));
        if (success) {
            class_replaceMethod(class, swizzledSelector, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));
        } else {
            method_exchangeImplementations(originalMethod, swizzledMethod);
        }
    });
}

-(WKNavigation *)post_loadRequest:(NSURLRequest *)request {
    if ([[request.HTTPMethod uppercaseString] isEqualToString:@"POST"]){
        NSString *url = request.URL.absoluteString;
        NSString *params = [[NSString alloc] initWithData:request.HTTPBody encoding:NSUTF8StringEncoding];
        if ([params containsString:@"="]) {
            params = [params stringByReplacingOccurrencesOfString:@"=" withString:@"\":\""];
            params = [params stringByReplacingOccurrencesOfString:@"&" withString:@"\",\""];
            params = [NSString stringWithFormat:@"{\"%@\"}", params];
        }else{
            params = @"{}";
        }
        NSString *postJavaScript = [NSString stringWithFormat:@"\
                             var url = '%@';\
                             var params = %@;\
                             var form = document.createElement('form');\
                             form.setAttribute('method', 'post');\
                             form.setAttribute('action', url);\
                             for(var key in params) {\
                             if(params.hasOwnProperty(key)) {\
                             var hiddenField = document.createElement('input');\
                             hiddenField.setAttribute('type', 'hidden');\
                             hiddenField.setAttribute('name', key);\
                             hiddenField.setAttribute('value', params[key]);\
                             form.appendChild(hiddenField);\
                             }\
                             }\
                             document.body.appendChild(form);\
                             form.submit();", url, params];
//        __block id result = nil;
//        __block BOOL isExecuted = NO;
        __weak typeof(self) wself = self;
        [self evaluateJavaScript:postJavaScript completionHandler:^(id object, NSError * _Nullable error) {
            if (error && [wself.navigationDelegate respondsToSelector:@selector(webView:didFailProvisionalNavigation:withError:)]) {
                dispatch_async(dispatch_get_main_queue(), ^{
                    [wself.navigationDelegate webView:wself didFailProvisionalNavigation:nil withError:error];
                });
            }
//            result = object;
//            isExecuted = YES;
        }];
//        while (isExecuted == NO) {
//            [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
//        }
        return nil;
    }else{
       return [self post_loadRequest:request];
    }
}