WKWebView评估JavaScript返回值 [英] WKWebView evaluate JavaScript return value

问题描述

我需要更改一个函数来评估从UIWebView到WKWebView的JavaScript。我需要在这个函数中返回求值结果。

I need to change a function to evaluate JavaScript from UIWebView to WKWebView. I need to return result of evaluating in this function.

现在，我正在打电话：

[wkWebView evaluateJavaScript:call completionHandler:^(NSString *result, NSError *error)
{
    NSLog(@"Error %@",error);
    NSLog(@"Result %@",result);
}];

但是我需要得到像返回值的结果，比如 UIWebView 。
你能建议一个解决方案吗？

But I need get result like return value, like in UIWebView. Can you suggest a solution?

推荐答案

这不再适用于iOS 12+。

我解决了这个问题通过等待结果直到返回结果值。

I solved this problem by waiting for result until result value is returned.

我用NSRunLoop等待，但我不确定这是不是最好的方式......

I used NSRunLoop for waiting, but I'm not sure it's best way or not...

这是我现在使用的类别扩展源代码。

Here is the category extension source code that I'm using now.

@interface WKWebView(SynchronousEvaluateJavaScript)
- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script;
@end

@implementation WKWebView(SynchronousEvaluateJavaScript)

- (NSString *)stringByEvaluatingJavaScriptFromString:(NSString *)script
{
    __block NSString *resultString = nil;
    __block BOOL finished = NO;

    [self evaluateJavaScript:script completionHandler:^(id result, NSError *error) {
        if (error == nil) {
            if (result != nil) {
                resultString = [NSString stringWithFormat:@"%@", result];
            }
        } else {
            NSLog(@"evaluateJavaScript error : %@", error.localizedDescription);
        }
        finished = YES;
    }];

    while (!finished)
    {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:[NSDate distantFuture]];
    }

    return resultString;
}
@end

示例代码）

NSString *userAgent = [_webView stringByEvaluatingJavaScriptFromString:@"navigator.userAgent"];

NSLog(@"userAgent: %@", userAgent);

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