Xcode 在UIWebView中将文本设置为textarea

我正在尝试将文本设置为UIWebView中的文本区域

<textarea class="GFS3D5JBNW" style="padding: 4px;border-radius: 5px;" placeholder="Some placeholder text ..." title="Some Title ..." tabindex="1"></textarea>

或

但没有成功：-（有人给我一个提示吗？

问题由

NSString *source = [NSString stringWithFormat:@"var inputFields = document.getElementsByTagName('textarea'); \
for (var i = inputFields.length >>> 0; i--;) {inputFields[i].value = '%@';}",input];
[self.mainWebView stringByEvaluatingJavaScriptFromString:source];

 NSString *source = [NSString stringWithFormat:@"var inputFields = document.getElementsByTagName('textarea').value = '%@';}", text];
[self.mainWebView stringByEvaluatingJavaScriptFromString: source];

NSString *source = [NSString stringWithFormat:@"var inputFields = document.getElementsByTagName('textarea'); \
for (var i = inputFields.length >>> 0; i--;) {inputFields[i].value = '%@';}",input];
[self.mainWebView stringByEvaluatingJavaScriptFromString:source];