passing objective c variable to javascript in ios

How to pass a ObjectiveC string Variable to a javascript function? I ha开发者_开发百科ve just started with javascript.. so plz 4give my ignorance...

NSString * param  = @"foo";   
NSString * jsCallBack = [NSString stringWithFormat:@"myFunc('%@')",param];
[webView stringByEvaluatingJavaScriptFromString:jsCallBack];

In Objective-C

NSString *str  = @"hi ya";   
[self.webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"myFunc('%@')",str]];

Now call this function in the js file:

function myFunc(str)
{
   alert(str);
}

These steps should work.