how to let two ViewControllers use one NSObject

If you have one NSObject that you want two ViewControllers to be able to use, how do yo开发者_StackOverflow中文版u know which ViewController is calling it so when you pass what ever data you are computing back, you pass it back to the correct ViewController.

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If you want the returned data to change based on the caller, create a method in the object you are retrieving data from rather than directly accessing a property.

In your NSObject, you could have a method that follows this format (my example is returning a string):

- (NSString *)getDataFor:(NSInteger)callingController {

    NSString *outputString = nil;

    if (callingController == 1) {
        // set value of output string for controller 1
    } else if (callingController == 2) {
        // set value of output string for controller 2
    }

    return outputString;

}

Then, from your view controller, you just call the method with the appropriate identifier as input.