Sync JavaScript in WKWebView

Create sync version

UIWebView javascript method is sync type.
On the other hand, WKWebView evaluateJavaScript:completionHandler: is async type.
Actually, we can get the result from callback method.
But, sometimes need sync type, waiting UI etc…

- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)javascript {
    __block NSString *res = nil;
    __block BOOL finish = NO;
    [self evaluateJavaScript:javascript completionHandler:^(NSString *result, NSError *error){
        res = result;
        finish = YES;
    }];

    while (!finish) {
        [[NSRunLoop currentRunLoop] runUntilDate:[NSDate dateWithTimeIntervalSinceNow:0.1]];
    }
    return res;
}

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