您必须实现数据源和代理。

$

   - （IBAction）usButtonPressed：（id）sender {
 self.inputArray = self.usArray; 
 [self.thePicker reloadAllComponents]; 
} 

  - （IBAction）mexicoButtonPressed：（id）sender {
 self.inputArray = self.mexicoArray; 
 [self.thePicker reloadAllComponents]; 
} 
 

数据源方法：

   - （NSInteger）numberOfComponentsInPickerView：（UIPickerView *）pickerView 
 {
 return 1; 
} 


  - （NSInteger）pickerView：（UIPickerView *）pickerView numberOfRowsInComponent：（NSInteger）component 
 {
 return [self.inputArray count] ; 
} 
 

委托方法：

   - （NSString *）pickerView：（UIPickerView *）pickerView titleForRow：（NSInteger）row forComponent：（NSInteger）component 
 {
 return [self.inputArray objectAtIndex：row]; 
} 
 

IF I wanted a picker, for states/provinces, i haven't seen an example, but I mocked up shown in the link above, a picker for US/Can/Mex. wondering can you dynamically switch the NSMutableArray for the UIPickerView and then have it somehow reload each time you click on US/Can/Mex buttons??? How do I go about doing this. What approach do I take. Looking for someone to point a beginner for a clue in the right direction.

You will have to implement the datasource and the delegate.

once you press a button, set an array pointer to the appropriate array.

than call [thePicker reloadAllComponents];

-(IBAction) usButtonPressed:(id)sender{
    self.inputArray = self.usArray;
    [self.thePicker reloadAllComponents];
}

-(IBAction) mexicoButtonPressed:(id)sender{
    self.inputArray = self.mexicoArray;
    [self.thePicker reloadAllComponents];
}

the datasource methods:

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 1;
}


- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return [self.inputArray count];
}

the delegate methods:

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    return [self.inputArray objectAtIndex:row];
}