WKWebView加载js遇到的问题

需求：hybrid混合开发，大概就是把.html和.css等资源文件存在本地，通过jsBridge.js来进行交互，提高在app中加载h5页面的加载速度和用户体验等问题，减少app端需要发包才能解决的一些业务问题。

最近将hybrid框架中的UIWebView换成WKWebView遇到的问题，主要是加载jsBridge.js文件遇到的问题。

1. UIWebView中的加载jsBridge.js，代码如下：

- (void)webViewDidStartLoad:(UIWebView *)webView
{
    if (webView != self) { return; }
    
    [webView stringByEvaluatingJavaScriptFromString:[self jsString]];
    
    if ([self.webViewDelegate respondsToSelector:@selector(webViewDidStartLoad:)]) {
        [self.webViewDelegate webViewDidStartLoad:webView];
    }
}

- (NSString *)jsString {
    NSString *result = [NSString stringWithContentsOfFile:JSBridgePath encoding:NSUTF8StringEncoding error:nil];
    if (result == nil) {
        result = [NSString stringWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"jsBridge" ofType:@"js"] encoding:NSUTF8StringEncoding error:nil];
    }
    return result;
}

像正常加载url的方法一样就可以了

- (void)reloadWebViewRequest
{
    [self.webView loadRequest:[NSURLRequest requestWithURL:self.url]];
}

2.WKWebView中的加载jsBridge.js，一开始也是直接像UIWebView一样在代理方法执行jsBridge.js，虽然js代码执行成功了，但是加载不了存在本地的.html和.css等文件，页面就加载不出来，代码如下：

- (void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation *)navigation
{
    if (webView != self) { return; }
    
    [webView evaluateJavaScript:[self jsString] completionHandler:^(id _Nullable, NSError * _Nullable error) {
        
    }];
    
    if ([self.webViewDelegate respondsToSelector:@selector(webView:didFinishNavigation:)]) {
        [self.webViewDelegate webView:webView didFinishNavigation:navigation];
    }
}

后来在网上找了好多资料，具体实现如下：

// 初始化webview
- (void)viewDidLoad {
    [super viewDidLoad];
    [self installStartTime];
    
    WKWebViewConfiguration *config = [[WKWebViewConfiguration alloc] init];
    self.webview = [[JSBWebView alloc] initWithFrame:self.view.bounds configuration:config];
    self.webview.navigationDelegate = self;
    self.webview.UIDelegate = self;
}

- (instancetype)initWithFrame:(CGRect)frame configuration:(WKWebViewConfiguration *)configuration
{
    WKUserScript *script = [[WKUserScript alloc] initWithSource:[self jsString] injectionTime:WKUserScriptInjectionTimeAtDocumentStart forMainFrameOnly:YES];
    [configuration.userContentController addUserScript:script];
    [configuration.preferences setValue:@YES forKey:@"allowFileAccessFromFileURLs"];

    self = [super initWithFrame:frame configuration:configuration];
    if (self) {
        [self setup];
    }
    return self;
}

说明，一定要设置[configuration.preferences setValue:@YES forKey:@"allowFileAccessFromFileURLs"];

参考资料：
https://stackoverflow.com/questions/36013645/setting-disable-web-security-and-allow-file-access-from-files-in-ios-wkwebvi

加载文件一定要用loadFileURL:allowingReadAccessToURL:这个才会生效

- (void)reloadWebViewRequest
{
    NSURL *accessURL = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] objectAtIndex:0];
    [self.webview loadFileURL:self.url allowingReadAccessToURL:accessURL];
}

参考资料：
https://stackoverflow.com/questions/40472796/wkwebview-loadfileurl-works-only-once