从UIWebView提取jSignature图像

Question

I am trying to extract signature bitmap from UIWebView .

This is HTML code:

<canvas class="jSignature" width="200" height="120" style="margin: 0px; padding: 0px; border: none; height: 120px; width: 200px;"></canvas>

This code works in JS:

$('.signature').jSignature('getData','image')

This is my piece of code:

NSString *sign = [self.webView stringByEvaluatingJavaScriptFromString:@"$('.signature').jSignature('getData','image')"];

So sign is:

<object returned empty description>

Is there any way to get error message from stringByEvaluatingJavaScriptFromString to debug this problem?

Answer 1

Found solution. Read doc of jSignature: http://willowsystems.github.io/jSignature/#/about/

So it should be:

NSString *sign = [self.webView stringByEvaluatingJavaScriptFromString:@"$('.signature').jSignature('getData')"];