通过JavaScriptCore实现OC与JS的交互
1 OC调用JS

NSString *versionCodeStr = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleShortVersionString"];
    NSString *jsStr = [NSString stringWithFormat:@"appVersionCode('%@')", versionCodeStr];
    [self.myWebView stringByEvaluatingJavaScriptFromString:jsStr];

在JS中JavaScript代码如下

function appVersionCode(versionCode){
        alert(versionCode)
    }

2 JS调用OC
2.1 block 方式

JSContext *context = [NSObject contextForWebView:self.myWebView];
    context[@"startLoad"] = ^ (NSString *flag) {
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"开始就添加");
        });
    };
    
    context[@"callShareAction"] = ^ (NSString *flag) {
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"分享");
        });
    };
    
    context[@"callReturnAction"] = ^ () {
        return @"最幸福的一天";
    };

在JS中调用方式如下

var callShare = function() {
        callShareAction(1)
    }
    var callAlert = function () {
        var str = callReturnAction()
        alert(str)
    }
    window.onload = function () {
        startLoad(1)
    }

2.2 注入模型的方式

JSContext *context = [NSObject contextForWebView:self.myWebView];
DMCallCameraModel *callCameraModel = [[DMCallCameraModel alloc] init];
context[@"callCameraModel"] = callCameraModel;

模型的定义，需要遵循JSExport协议

#import <Foundation/Foundation.h>
#import <JavaScriptCore/JavaScriptCore.h>

@protocol DMCallCameraExport <JSExport>

- (void)callCameraAction:(BOOL)bFlag;

- (void)callMultiArgumentsAction:(NSString *)firstStr titleStr:(NSString *)secondStr;

@end

@interface DMCallCameraModel : NSObject <DMCallCameraExport>

@end

模型的实现

- (void)callCameraAction:(BOOL)bFlag
{
    NSLog(@"callCameraAction");
}

- (void)callMultiArgumentsAction:(NSString *)firstStr titleStr:(NSString *)secondStr
{
    NSLog(@"参数一:%@, 参数二:%@", firstStr, secondStr);
}

@end

在JS中的调用方式如下

var callCamera = function() {
        callCameraModel.callCameraAction(1)
    }
    var callSubmit = function() {
        callCameraModel.callMultiArgumentsActionTitleStr("Hello", "World")
    }

注：多个参数时，在JS中调用时使用驼峰法并去掉冒号
3 关于JSContext的获取时机

#import <UIKit/UIKit.h>
#import <JavaScriptCore/JavaScriptCore.h>

@interface NSObject (JSContextTracker)

+ (JSContext *)contextForWebView:(UIWebView *)webView;

@end

#import "NSObject+JSContextTracker.h"
#import "DMNotificationName.h"

@implementation NSObject (JSContextTracker)

+ (NSMapTable *)JSContextTrackerMap
{
    static NSMapTable *contextTracker;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        contextTracker = [NSMapTable strongToWeakObjectsMapTable];
    });
    
    return contextTracker;
}

- (void)webView:(id)unused didCreateJavaScriptContext:(JSContext *)ctx forFrame:(id)alsoUnused
{
    NSAssert([ctx isKindOfClass:[JSContext class]], @"bad context");
    if (!ctx)
        return;
    NSMapTable *map = [NSObject JSContextTrackerMap];
    static long contexts = 0;
    NSString *contextKey = [NSString stringWithFormat:@"jsctx_%@", @(contexts++)];
    [map setObject:ctx forKey:contextKey];
    ctx[@"JSContextTrackerMapKey"] = contextKey; // store the key to the map in the context itself

    [[NSNotificationCenter defaultCenter] postNotificationName:DMWebviewCreateContextNotification object:nil];
}

+ (JSContext *)contextForWebView:(UIWebView *)webView
{
    // this will trigger didCreateJavaScriptContext if it hasn't already been called
    NSString *contextKey = [webView stringByEvaluatingJavaScriptFromString:@"JSContextTrackerMapKey"];
    JSContext *ctx = [[NSObject JSContextTrackerMap] objectForKey:contextKey];
    
    return ctx;
}

@end

我们观察通知，并通过contextForWebView方法获取JSContext

[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(webViewDidCreateContext:) name:DMWebviewCreateContextNotification object:nil];

- (void)webViewDidCreateContext:(NSNotification *)notify
{
    if (self.isShowing) {
        NSLog(@"***********  页面正在显示 **************");
    } else {
        NSLog(@"*********** 页面已经消失 **************");
        return;
    }
    JSContext *context = [NSObject contextForWebView:self.myWebView];
}

4 JS中的代码如下

<!DOCTYPE html>
<html>
<head lang="en">
     <meta charset="UTF-8">
</head>
<body>
     <div style="margin-top: 40px"> 
        <h3>Objective-C和JavaScript交互的那些事</h3> 
        <input type="button" value="CallCamera" onclick="callCamera()">
      </div>

       <div>
         <input type="button" value="Share" onclick="callShare()"> 
       </div>
       
       <div>
           <input type="button" value="Submit" onclick="callSubmit()">
        </div>
<script>
    var callCamera = function() {
        callCameraModel.callCameraAction(1)
    }
    var callSubmit = function() {
        callCameraModel.callMultiArgumentsActionTitleStr("Hello", "World")
    }
    var callShare = function() {
        callShareAction(1)
    }
    var callAlert = function () {
        var str = callReturnAction()
        alert(str)
    }
    window.onload = function () {
        startLoad(1)
    }
    function appVersionCode(versionCode){
        alert(versionCode)
    }
</script>

</body>
</html>

5 效果如下

0.png

点击CallCamera、Share、Submit输出log如下

1.png

- (void)alertBtnClicked:(id)sender
{
    [self.myWebView stringByEvaluatingJavaScriptFromString:@"callAlert()"];
}

先OC调用JS的callAlert方法，callAlert方法中JS有调用OC的callReturnAction方法返回字符串，然后JS中弹出返回的字符串

2.png

点击保存如下

- (void)saveBtnClicked:(id)sender
{
    NSString *versionCodeStr = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleShortVersionString"];
    NSString *jsStr = [NSString stringWithFormat:@"appVersionCode('%@')", versionCodeStr];
    [self.myWebView stringByEvaluatingJavaScriptFromString:jsStr];
}

3.png