Question

I wanna to know abt "stringByEvaluatingJavaScriptFromString".

According to the apple doc.
"The result of running script or nil if it fails."

I have a method in which inside a for loop i’m passing a string value to stringByEvaluatingJavaScriptFromString. what will it do ?? will this get response for every string or something else will happen??
I was doing like this…

- (void)loadWithStartPoint:(NSString *)startPoint endPoint:(NSMutableArray *)endPoints options:(UICGDirectionsOptions *)options {
    for (int idx = 0; idx < [endPoints count]; idx ++) 
    {
        NSString *msg = [NSString stringWithFormat:@"loadDirections('%@', '%@', %@)", startPoint, [endPoints objectAtIndex:idx], [options JSONRepresentation]];
        [googleMapsAPI stringByEvaluatingJavaScriptFromString:msg];
    }
}

Inorder to get response to every string what should I do? I think that it should get response to every string that i’m passing here. Please tell me what m doing wrong and how would i manipulate my code to get response to all strings that m passing.
Any help would be appreciated .Thnx in advance.

Answer 1

You should make your javascript method to return a default string or something if even an error occurs in the script.

function loadDirections()
{

try
  {
  //Your code goes here which returns some result
  }
catch(err)
  {
  var errorFlag = "ERROR";
return errorFlag;
  }
}

and then you should alter your Objective C code like below

NSString *msg = [NSString stringWithFormat:@"loadDirections('%@', '%@', %@)", startPoint, [endPoints objectAtIndex:idx], [options JSONRepresentation]];

if([msg isEqualToString:@"ERROR")
{

//Do some error handling

}
else
{

//Your actual code goes here

}

Update for the comment:

To solve your javascript asynchronous problem either (1) you can change your design and call the javascript method only after getting response from the first call (2) or else you can use NSTimer which will will give a little time for the execution. In my opinion changing your design as per the first option would be perfect.

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