从Objective-C将大数据传递到UIWebView JavaScript

Question

I've got an app which uses a UIWebView to display an HTML page, loaded off a server. This works great, including the Objective-C part that loads additional data, however, what does not work is passing data to the JavaScript running in the WebView.

What I've tried is:

NSString * sigstring = [NSString stringWithFormat:@"updatedSig('%@');", [thisSignature base64EncodedString]];
sigstring = [sigstring stringByReplacingOccurrencesOfString:@"\n" withString:@""];

NSLog(@"WV: %@",[[[(AppDelegate*)[[UIApplication sharedApplication] delegate] viewController] webView] stringByEvaluatingJavaScriptFromString:sigstring]);

The updatedSig function echos to the console whatever is passed in.

However, in this case, it returns nothing to the console, when there should be data there.

To test for other issues, I've also tried

NSString * sigstring = [NSString stringWithFormat:@"updatedSig('%@');", @"AbsolutelyAnything"];
sigstring = [sigstring stringByReplacingOccurrencesOfString:@"\n" withString:@""];

NSLog(@"WV: %@",[[[(AppDelegate*)[[UIApplication sharedApplication] delegate] viewController] webView] stringByEvaluatingJavaScriptFromString:sigstring]);

This worked perfectly, it displays "AbsolutelyAnything" in the console just fine.

Any help would be much appreciated.

Answer 1

Is your updated signature greater than 10MB or take more than 10 seconds to execute? The documentation mentions those limitations.

Also keep in mind that the result of stringByEvaluatingJavaScriptFromString is the executed Javascript, so if something goes wrong while executing you will likely just receive nil. Is the NSLog executing at all in the first example?

Assuming you are obeying the limitations, my recommendation would be to insert alerts in the Javascript to ensure that it's executing as you expect.