一、OC调用js

- (void)webViewDidFinishLoad:(UIWebView *)webView
{
    self.title = [webView stringByEvaluatingJavaScriptFromString:@"doucument.title;"];
}

二、js调用OC

1. 无参

• 在js中定义一个自己的协议头

<script>
  function method()
{
  //login为oc方法
   location.href = 'keven://login';
}
</script>

• 方法调用

//拦截请求
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
    NSString *url = request.URL.absoluteString;
    NSString *scheme = @"keven://";
    if ([url hasPrefix:scheme]) {
        //截取方法名
        NSString *methodName = [url substringFromIndex:scheme.length];
        //调用方法
        [self performSelector:NSSelectorFromString(methodName) withObject:nil];
        return NO;
    }
    return YES;
}

2. 有参

• 一个参数的时候

[self performSelector:NSSelectorFromString(methodName) withObject:param];

• 两个参数的时候

[self performSelector:NSSelectorFromString(methodName) withObject:firstParam withObject:secondParam];

• 多个参数的时候（使用NSInvocation，同样适用于一个或者两个参数）
  a. 给nsobject写分类

#import "NSObject+Extension.h"

@implementation NSObject (Extension)
- (id)performSelector:(SEL)selector withObjects:(NSArray *)objects
{
    // 方法签名(方法的描述)
    NSMethodSignature *signature = [[self class] instanceMethodSignatureForSelector:selector];
    if (signature == nil) {
//        @throw [NSException exceptionWithName:@"牛逼的错误" reason:@"方法找不到" userInfo:nil];
        [NSException raise:@"牛逼的错误" format:@"%@方法找不到", NSStringFromSelector(selector)];
    }
    
    // NSInvocation : 利用一个NSInvocation对象包装一次方法调用（方法调用者、方法名、方法参数、方法返回值）
    NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:signature];
    invocation.target = self;
    invocation.selector = selector;
    
    // 设置参数
    NSInteger paramsCount = signature.numberOfArguments - 2; // 除self、_cmd以外的参数个数
    paramsCount = MIN(paramsCount, objects.count);
    for (NSInteger i = 0; i < paramsCount; i++) {
        id object = objects[i];
        //传入空参数的时候的处理
        if ([object isKindOfClass:[NSNull class]]) continue;
        //从2开始，应为索引0和1被占用了
        [invocation setArgument:&object atIndex:i + 2];
    }
    
    // 调用方法
    [invocation invoke];
    
    // 获取返回值
    id returnValue = nil;
    if (signature.methodReturnLength) { // 有返回值类型，才去获得返回值
        [invocation getReturnValue:&returnValue];
    }
    
    return returnValue;
}
@end

b. 在控制器中调用

[self performSelector:@selector(sendMessage:number2:number3:) withObjects:@[
                                                                        [NSNull null],
                                                                        [NSNull null],
                                                                        @"10010"
                                                                        ]];
//等价于==》
[self sendMessage:nil number2:nil number3:@"10010"];

c. For Example

/**
 * 通过这个方法完成JS调用OC
 * JS和OC交互的第三方框架：WebViewJavaScriptBridge
 */
- (BOOL)webView:(UIWebView *)webView shouldStartLoadWithRequest:(NSURLRequest *)request navigationType:(UIWebViewNavigationType)navigationType
{
    // url == xmg://sendMessage_?200
    NSString *url = request.URL.absoluteString;
    NSString *scheme = @"xmg://";
    if ([url hasPrefix:scheme]) {
        // 获得协议后面的路径  path == sendMessage_number2_?200&300
        NSString *path = [url substringFromIndex:scheme.length];
        // 利用?切割路径
        NSArray *subpaths = [path componentsSeparatedByString:@"?"];
        // 方法名 methodName == sendMessage:number2:
        NSString *methodName = [[subpaths firstObject] stringByReplacingOccurrencesOfString:@"_" withString:@":"];
        // 参数  200&300
        NSArray *params = nil;
        if (subpaths.count == 2) {
            params = [[subpaths lastObject] componentsSeparatedByString:@"&"];
        }
        // 调用
        [self performSelector:NSSelectorFromString(methodName) withObjects:params];
        
        return NO;
    }
    
    NSLog(@"想加载其他请求，不是想调用OC的方法");
    
    return YES;
}