iPhone SDK：如何将值数组从ViewController传递到其他ViewController？

Question

I tried creating a method like below in SecondViewController :

-(void)setValue:(NSMutableArray*)array
 { 
      //NSMutableArray *newArray = [[NSMutableArray alloc] init];
      newArray = [array retain];
 }

and passing the value from FirstViewController using an object of SecondViewController named second:

[second setValue:existingArray];

existingArray is an NSMutableArray.

What could be wrong?

Answer 1

In the code you have set the array in the " second " object of a SecondViewController .

So you need to use that object for displaying the SecondeViewController , other wise how can it won't show the array.

Check the following code.

 //   In the FirstViewController

- (void)buttonClicked:(id)sender{

    SecondViewController *second = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle: nil];
 [second setValue:existingArray];
 [self.navigationController pushViewController:second animated:YES];
 [second release];

}

Here in the code I am assigning the data to the array in the "second" object and I am using that object to display the controller.

Regards,

Satya

Answer 2

You could use a property instead of the setter you have there(which looks bad). Question is do you really need to do a copy on the array or a retain would be enough?

Create a NSMutableArray *myArray as a local variable in the SecondViewController. Add a property @property(nonatomic, retain) NSMutableArray *myArray; in the interface.

Synthesize it and to set it just call [mySecondViewController setMyArray:newArray];

If you have instantiated correctly the SecondViewController and if the array that you want to send is not nil then it should work.

if you do it like this:

-(void)setValue:(NSMutableArray*)array
 { 
      NSMutableArray *newArray = [[NSMutableArray alloc] init];
      newArray = [array mutableCopy];
 }

newArray would be a variable declared inside the SetValue method, after the program exits the setValue method, the newArray variable will not be accessible anymore. Also you leak memory because newArray is never released.