我需要更改一个函数，将JavaScript从UIWebView判断为WKWebView.我需要返回这个函数中的求值结果.
现在，我打电话:
[wkWebView evaluateJavaScript:call completionHandler:^(NSString *result, NSError *error)
{
NSLog(@"Error %@",error);
NSLog(@"Result %@",result);
}];
但我需要得到返回值这样的结果，比如UIWebView.
Update: This is not working on iOS 12+ anymore.
我通过等待结果直到返回结果值来解决这个问题.
我用nsrunlop等待，但我不确定这是不是最好的方式...
下面是我现在使用的类别扩展源代码:
@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);