UITextField – A Complete API Overview

    January 4th, 2010 Posted by: - posted under:Tutorials

    The UITextField is probably one of the most commonly used UI controls on the iPhone. It is the primary method of user input via the keyboard and provides a great deal of additional functionality.

    With the success of our las API tutorial on NSArray, I thought I would do another walkthrough, this time on UITextField. I will be explaining all of the properties for it as well as bringing up some functionality that you may not have known about.

    Text Attributes

    The attributes have to do with the actual text inside of the UITextField.

    text The text displayed in the UITextField
    placeholder The text that gets displayed prior to the user entering in anything. This text is usually a lighter color than the primary text to denote that it will be replaced.
    font The font of the text to be displayed. You can set it like this
    textColor The color of the text that is displayed
    textAlignment How the text is aligned in the UITextField. The possible values for this are UITextAlignmentLeft, UITextAlignmentRight, UITextAlignmentCenter

    Here are some examples of using these properties.

    // Setting the text
    [myTextField setText:@"This is some text!"];
    // Setting the placeholder
    [myTextField setPlaceholder:@"Type text here"];
    // Setting the font.
    [myTextField setFont:[UIFont fontWithName:@"Times New Roman" size:14]];
    // Setting the text color
    [myTextField setTextColor:[UIColor blueColor]];
    // Setting the text alignment
    [myTextField setTextAlignment:UITextAlignmentCenter];

    Here is what the UITextField would look like after we update these properties.

    Adjusting the size of the text in the UITextField

    The text displayed in our UITextField can be dynamically sized based on the width of the UITextField. The benefit of this is all of the text being typed will be visible on the screen. It will shrink the text down until it reaches the default font size of 17. So, for this to make sense, you must set the font size of the UITextField to something larger than 17.

    adjustsFontSizeToFitWidth Boolean value denoting whether to fit the font size to the width of the UITextField.

    Here is an example of using these properties.

    [myTextField setFont:[UIFont fontWithName:@"Times New Roman" size:30]];
    [myTextField setAdjustsFontSizeToFitWidth:YES];

    Here are some screenshots of the text shrinking when typing in the UITextField.

    Managing the editor’s behavior

    These two properties are pretty straight forward.

    editing Read-only boolean value letting you know if the user is currently editing the UITextField
    clearsOnBeginEditing Clears the text in the field every time the user begins to edit it.

    Not very exciting and probably doesn’t even deserve an example…

    Setting the view’s background appearance

    This group of properties defines how the UITextField will look. If you have ever seen a fancy input box, this is how they are doing it.

    borderStyle Defines the type of border for the UITextField. Possible choices are UITextBorderStyleNone, UITextBorderStyleLine, UITextBorderStyleBezel, and UITextBorderStyleRoundedRect. The default is UITextBorderStyleNone.
    background A UIImage representing the background image of the UITextField when it’s enabled. If this field is altered the borderStyle property is ignored.
    backgroundDisabled A UIImage representing the background image of the UITextField when it’s disabled.

    Here is are some example of using each of the border styles

    // Border Style None
    [myTextField setBorderStyle:UITextBorderStyleNone];

    // Border Style Line
    [myTextField setBorderStyle:UITextBorderStyleLine];

    // Border Style Bezel
    [myTextField setBorderStyle:UITextBorderStyleBezel];

    // Border Style Rounded Rect
    [myTextField setBorderStyle:UITextBorderStyleRoundedRect];

    The border style is not terribly exciting. However, you can really spruce up your UITextFields using the background property. Here is an example of setting the background property to this image.

    myTextField.textAlignment = UITextAlignmentCenter;
    myTextField.textColor = [UIColor whiteColor];
    myTextField.borderStyle = UITextBorderStyleNone;
    myTextField.background = [UIImage imageNamed:@"bg.png"];

    and the result… Looks pretty good ehh? One GOTCHA that I want to point out here is, to get the background property to work correctly, you must set the boderStyle to anything other than UITextBorderStyleRoundedRect. Otherwise, the default UITextField will be displayed.
    Setting the view’s background appearance

    Managing Overlay Views

    Another interesting way of customizing your UITextFields is to use an overlay. UITextField offers a left and right overlay for your UITextFields. Here are the properties:

    clearButtonMode The circled X that gets displayed when typing. Used to clear out the text. Possible values: UITextFieldViewModeNever, UITextFieldViewModeWhileEditing, UITextFieldViewModeUnlessEditing, UITextFieldViewModeAlways
    leftView The view that appears to the left inside a UITextField. This could be something like a magnifying glass for search.
    leftViewMode Works like clearButtonMode, but toggles the leftView.
    rightView Same as leftView, except it aligns to the right.
    rightViewMode Same as leftViewMode but controls the rightView

    Let’s take a look at how adjusting the leftView works:

    UIImageView * myView = [[ UIImageView  alloc ]  initWithImage :
                    [UIImage  imageNamed : @"wordpress.png" ]];
    [myTextField  setLeftView :myView];
    [ myTextField   setLeftViewMode: UITextFieldViewModeAlways];
    [myView release ];

    As you can see, the text aligns after the image. This is a very simple way to really spruce up your UITextFields.

    The last thing we are going to discuss is showing and hiding the keyboard.

    Showing and Hiding The Keyboard

    To show the keyboard:

    [myTextField becomeFirstResponder];

    To hide the keyboard

    [myTextField resignFirstResponder];

    Well, I hope you have enjoyed this tutorial on the UITextField. I would love to see links to some interesting custom UITextFields in the comments, so please post them. Thanks for reading and happy iCoding!