How to enumerate through UITextFields on iOS

Question

Which is the correct way of enumerating through sub views to find text fields?

NSMutableArray *mutableTFs = [[NSMutableArray alloc] init];

for (UIView *view in [self.view subviews]) {
    if ([view isKindOfClass:[UITextField class]]) {            
        [mutableTFs addObject:view];
    }
}

OR

NSMutableArray *mutableTFs = [[NSMutableArray alloc] init];

for (UITextField *textField in [self.view subviews]) {
    [mutableTFs addObject:textField];
}

I know this isn't the correct wording, but what I don't understand is if it is the top method, how do you 'convert' it from a view to a text field?

You previous question [here](http://stackoverflow.com/questions/6753108/uitextfield-questions-input-accessory-and-enumeration) in case anyone's interested. — bshirley, Jul 21 '11 at 20:10
"how do you 'convert' it from a view to a text field?" - UITextField inherits from UIView, so every UITextField is a UIView. You didn't convert it to a UIView, you type casted it, telling the compiler that any method on UIView will work on this object. You would want the 2nd approach if you are going to be using UITextField methods as you iterate over the objects, using the corrected functions described below, don't use the one you have in your post :P — ColdLogic, Jul 21 '11 at 20:16

score 10 · Accepted Answer · edited May 23 '17 at 12:11

10

Which is the correct way of enumerating through sub views to find text fields?

The first method is the correct one. The second method will iterate over all the subviews, not just the subviews with type UITextField. The type in the for() is only a hint to the compiler.

For more information, see this question.

how do you 'convert' it from a view to a text field?

This is what typecasting is for.

for (UIView *view in [self.view subviews]) {
    if ([view isKindOfClass:[UITextField class]]) {
        // you don't need to cast just to add to the array         
        [mutableTFs addObject:view];
        // typecasting works as it does in C
        UITextField *textField = (UITextField *)view;
        // do something with textField
    }
}

edited May 23 '17 at 12:11

Community

1
1

answered Jul 21 '11 at 19:47

albertamg

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Thanks - need to look up on typecasting, never heard of it till now! – Alex Coplan Jul 21 '11 at 21:19
@Alex Coplan You are welcome :) You can start looking [here](http://stackoverflow.com/search?q=%5Bobjective-c%5D+cast+object). – albertamg Jul 21 '11 at 21:32

score 0 · Answer 2 · edited Jun 01 '13 at 12:45

Here's the best way.

// Make sure you're releasing this!
NSMutableArray *textFields = [[NSMutableArray alloc] init];

for (UITextField *textField in [self.view subviews]) {
    if ([textField isKindOfClass:[UITextField class]]) {
        [textFields addObject:textField];
    }
}

By specifying UITextField * as the type that you're performing the fast enumeration with, you'll be working with values that are casted already (by fast enumeration) from id to UITextField *. This does not guarantee that they are actually UITextFields though, so you still need a runtime check, in this case isKindOfClass:, to make sure the object you're currently working is really a UITextField.

So, both of them are correct, but only when combined.

Erik B · Answer 3 · 2011-07-21T19:56:14.907

The first method is the only working method of the two.

The second method would add all subviews to the array. That is if you would change subViews to subviews.

You could do the following:

for (UITextField *textField in [self.view subviews]) {
    if ([textField isKindOfClass:[UITextField class]]) {            
        [mutableTFs addObject:textField];
    }
}

That way you wouldn't have to convert the view to a text field to do something text field specific instead of just adding it to an array.

EDIT: If you don't want to convert to a text field right away, maybe because you're looking for both text fields and text views. This is how you'd convert it later:

for (UIView *view in [self.view subviews]) {
    if ([view isKindOfClass:[UITextField class]]) {            
        UITextField *textField = (UITextField *)view;
        // Do whatever you want with the text field.
    }
    if ([view isKindOfClass:[UITextView class]]) {            
        UITextView *textView = (UITextView *)view;
        // Do whatever you want with the text view.
    }
}

How to enumerate through UITextFields on iOS

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