How to dynamically adjust method names and calls with Objective-C

Question

I am trying to condense my code for a method and was wondering how I would achieve the following:

I have a bunch of variables that differ only in their number such as:

int intVariable1
int intVariable2
UILabel Label1
UILabel Label2
BOOL bool1
BOOL bool2

etc.

So I want to call a method and pass in an int. That int would determine which ints, UILablels, and BOOLs get worked on. So if a 1 was passed in the method would work on these variables like this:

- (void) DyanamicMethod: (int) inputNumber {
     //something that uses the inputNumber to act on the 1 variables

     intVariable1 = someValue;
     [Label1 setText:someText];
     bool1 = YES;
}

Obviously if a 2 were passed in I would want the variables to be of the 2 type. I'm assuming you would do something with creating a string somehow, but I'm not sure how to adjust that to use it to become a variable name. Any insight would be appreciated. Thank you for your time.

Answer 1

Declare the variables as arrays:

int intVariable[2];
UILabel *Label[2];
BOOL bools[2];

Then the method would look like this:

intVariable[inputNumber] = someValue;
[Label[inputNumber] setText:@"someText"];
bools[inputNumber] = YES;

Keep in mind that array indexes are zero-based so in the arrays above, variable "1" is at index 0 and variable "2" is at index 1. Your method could also just take the inputNumber and subtract one from it to get the array index.

Answer 2

You can use key-value coding.

- (void) DyanamicMethod: (int) inputNumber {
     //something that uses the inputNumber to act on the 1 variables

     NSString* key = [NSString stingWithFormat:@"Label%i", number];
     UILabel* label = [self valueForKey:key];
     label.text = newString;
}

Answer 3

If you needed something like that you could keep an NSArray of all of the labels ... Like in the class interface section:

NSArray* labels ;

In init:(or loadView)

labels = [[NSArray alloc] initWithObjects:Label1, Label2,etc] ;

In dealloc:

[labels release] ;

in DyanamicMethod: (int) inputNumber

UILabel* label = [labels objectAtIndex:inputNumber] ;

Repeat for each type ... Or make a new class holding the label, int and the bool, and have the array be of that type.

Another way might be:
Make properties for each of your member variables.
Then in your function:

UILabel label1 = [self performSelector:sel_getUid([[NSString stringWithFormat:@"label%d", inputNumber] UTF8String])] ;

I think using an array of some sort is better for this situation, but its possible to do it this way. See NSObject Documentation for performSelector.

Answer 4

You could do this with properties (well, you don't NEED properties, but they'd make it simpler), though you'd have to switch to objects:

@property (nonatomic, readwrite, retain) NSNumber *variable1, *variable2;
@property (nonatomic, readwrite, retain) NSNumber *bool1, *bool2;
@property (nonatomic, readwrite, retain) UILabel *label1, *label2;

- (void) DyanamicMethod: (int) inputNumber { 
    [[self valueForKey: [NSString stringWithFormat: @"label%d", inputNumber] setText: someText];
    [self setValue: [NSNumber numberWithInt: inputNumber] 
            forKey: [NSString stringWithFormat: @"variable%d", inputNumber]];
    [self setValue: [NSNumber numberWithBool: YES] 
            forKey: [NSString stringWithFormat: @"bool%d", inputNumber]];
}

Answer 5

Do you have too many variables for a simple switch statement?

switch(inputNumber) {
  case 1:
    intVariable1 = someValue;
    [Label1 setText:someText];
    bool1 = YES;
    break;
  case 2:
    intVariable2 = someValue;
    [Label2 setText:someText];
    bool2 = YES;
    break;
// etc
}