UIAlertController text alignment

Question

Is there a way to change the alignment of the message displayed inside a UIAlertController on iOS 8?

I believe accessing the subviews and changing it for the UILabel is not possible anymore.

Draggle

Answer 1

I have successfully used the following, for both aligning and styling the text of UIAlertControllers:

let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = NSTextAlignment.Left

let messageText = NSMutableAttributedString(
    string: "The message you want to display",
    attributes: [
        NSParagraphStyleAttributeName: paragraphStyle,
        NSFontAttributeName : UIFont.preferredFontForTextStyle(UIFontTextStyleBody),
        NSForegroundColorAttributeName : UIColor.blackColor()
    ]
)

myAlert.setValue(messageText, forKey: "attributedMessage")

You can do a similar thing with the title, if you use "attributedTitle", instead of "attributedMessage"

Swift 3 update

The above still works in Swift 3, but the code has to be slightly altered to this:

let messageText = NSMutableAttributedString(
    string: "The message you want to display",
    attributes: [
        NSParagraphStyleAttributeName: paragraphStyle,
        NSFontAttributeName : UIFont.preferredFont(forTextStyle: UIFontTextStyle.body),
        NSForegroundColorAttributeName : UIColor.black
    ]
)

myAlert.setValue(messageText, forKey: "attributedMessage")

Swift 4 update

let messageText = NSMutableAttributedString(
    string: "The message you want to display",
    attributes: [
        NSAttributedStringKey.paragraphStyle: paragraphStyle,
        NSAttributedStringKey.font: UIFont.preferredFont(forTextStyle: UIFontTextStyle.body),
        NSAttributedStringKey.foregroundColor: UIColor.black
    ]
)

myAlert.setValue(messageText, forKey: "attributedMessage")

Swift 5 update

let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.alignment = alignment
let messageText = NSAttributedString(
    string: "message",
    attributes: [
        NSAttributedString.Key.paragraphStyle: paragraphStyle,
        NSAttributedString.Key.foregroundColor : UIColor.primaryText,
        NSAttributedString.Key.font : UIFont(name: "name", size: size)
    ]
)

myAlert.setValue(messageText, forKey: "attributedMessage")

Fca

Seems like this is private API use, did this make it into the App Store? – Marsipobranch

@Marsipobranch yes, it did. – Fca

What's private about it? – Nimwegen

Is there any objective-c version? – Susumu

@SonicMaster sorry, but I don't have experience with Objective-C. I guess, since this is mainly assignments and calling functions, the translation should be straightforward. – Fca

I tried to see if this method works for changing text alignment when using UIAlertAction items in UIAlertController as well, but it resulted in some key-value compliance and undefined key exceptions and the controller not displaying. – Melchor

Update for Swift 4 let paragraphStyle = NSMutableParagraphStyle() paragraphStyle.alignment = NSTextAlignment.justified let messageText = NSMutableAttributedString( string: alertMsg, attributes: [ NSAttributedStringKey.paragraphStyle: paragraphStyle, NSAttributedStringKey.font : UIFont.preferredFont(forTextStyle: UIFontTextStyle.body), NSAttributedStringKey.foregroundColor : UIColor.black ] ) – Chaff

Is there any documentation for keys like "attributedMessage" and "attributedTitle"? How will I get a list of all available keys? – Grayling

@AkhilShrivastav google "UIAlertAction runtime headers", there are tons of undocumented keys that can be used to customize native components – Stacked

Answer 2

Use the below code

UIAlertController * alert = [UIAlertController
                                 alertControllerWithTitle:[title lowercaseString]
                                 message:[message lowercaseString]
                                 preferredStyle:UIAlertControllerStyleAlert];

    if (alertStyle == kUIAlertStylePlainText)
    {
        [alert addTextFieldWithConfigurationHandler:^(UITextField *textField) {

        }];
    }

    if (okTitle) {
        UIAlertAction* ok = [UIAlertAction actionWithTitle:[okTitle lowercaseString] style:UIAlertActionStyleDefault
                                                   handler:^(UIAlertAction * action) {
                                                       callback(alert, action, nil);
                                                   }];
        [alert addAction:ok];
    }

    if (cancelTitle) {
        UIAlertAction* cancel = [UIAlertAction actionWithTitle:[cancelTitle lowercaseString] style:UIAlertActionStyleDefault
                                                       handler:^(UIAlertAction * action) {
                                                           callback(alert, nil, action);
                                                       }];
        [alert addAction:cancel];
    }


    NSMutableParagraphStyle *paraStyle = [[NSMutableParagraphStyle alloc] init];
    paraStyle.alignment = NSTextAlignmentLeft;

    NSMutableAttributedString *atrStr = [[NSMutableAttributedString alloc] initWithString:[message lowercaseString] attributes:@{NSParagraphStyleAttributeName:paraStyle,NSFontAttributeName:[UIFont systemFontOfSize:13.0]}];

    [alert setValue:atrStr forKey:@"attributedMessage"];
    [viewInstance presentViewController:alert animated:YES completion:nil];

Kandrakandy

this is straight forward and does not seem too hacky, should be stable for a while – Faust

Answer 3

I took up @Amos's answer and made it into a convenient extension:

public extension UIAlertController {

    func setMessageAlignment(_ alignment : NSTextAlignment) {
        let paragraphStyle = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
        paragraphStyle.alignment = alignment

        let messageText = NSMutableAttributedString(
            string: self.message ?? "",
            attributes: [
                NSAttributedString.Key.paragraphStyle: paragraphStyle,
                NSAttributedString.Key.font: UIFont.systemFont(ofSize: 12),
                NSAttributedString.Key.foregroundColor: UIColor.gray
            ]
        )

        self.setValue(messageText, forKey: "attributedMessage")
    }
}

Then you can simply set the alignment value: myAlert.setMessageAlignment(.left)

Humperdinck

Answer 4

Navigate to subview tree until you get to the UILabels for the title and the message

NSArray *viewArray = [[[[[[[[[[[[alertController view] subviews] firstObject] subviews] firstObject] subviews] firstObject] subviews] firstObject] subviews] firstObject] subviews];
UILabel *alertTitle = viewArray[0]
UILabel *alertMessage = viewArray[1];
alertMessage.textAlignment = NSTextAlignmentLeft;

However, you may want to make an category for it

@interface UIAlertController (ShowMeTheLabels)

@property (nonatomic, strong) UILabel *titleLabel, *messageLabel;

@end

@implementation UIAlertController (ShowMeTheLabels)
@dynamic titleLabel;
@dynamic messageLabel;

- (NSArray *)viewArray:(UIView *)root {
    NSLog(@"%@", root.subviews);
    static NSArray *_subviews = nil;
    _subviews = nil;
    for (UIView *v in root.subviews) {
        if (_subviews) {
            break;
        }
        if ([v isKindOfClass:[UILabel class]]) {
            _subviews = root.subviews;
            return _subviews;
        }
        [self viewArray:v];
    }
    return _subviews;
}

- (UILabel *)titleLabel {
    return [self viewArray:self.view][0];
}

- (UILabel *)messageLabel {
    return [self viewArray:self.view][1];
}

@end

Then you can align the text like this

yourAlertController.messageLabel.textAlignment = NSTextAlignmentLeft;

Selfassurance

NSArray *viewArray = [[[[[[[[[[[[alertController view] subviews] firstObject] subviews] firstObject] subviews] firstObject] subviews] firstObject] subviews] firstObject] subviews]; That takes the cake for most nested ObjC I've never seen o.0 – Diarmit

Yes. Apple doesn't really want people to mess with it. It's is a far better investment to make a custom pop up alert than to tinker with something so deeply nested. – Selfassurance

They never did come through with their promise, in one of the 2013 sessions they mentioned that they added a UIView property so that we could put whatever we want in there... It never made it in. – Diarmit

Actually this is the correct modern answer for the current API I guess! It works like a charm! Sweet! Thanks man! – Aerospace

Has someone make it to the app store? – Susumu

It crashes on iOS 11 (tested on real device): 'NSInvalidArgumentException', reason: '-[UIView setTextAlignment:]: unrecognized selector sent to instance... – Talented

Answer 5

Swift 4.2 + multiline string linebreak indentation

let paragraphStyle = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle

paragraphStyle.headIndent = 14

let messageText = NSMutableAttributedString(
    string: "... multiline string need linebreak indentation ...",
    attributes: [
        NSAttributedString.Key.paragraphStyle: paragraphStyle,
        NSAttributedString.Key.font: UIFont.systemFont(ofSize: 12),
        NSAttributedString.Key.foregroundColor: UIColor.gray
    ]
)

alert.setValue(messageText, forKey: "attributedMessage")

Gielgud

Answer 6

The following method will set the text alignment, while preserving the default font size.

static void makeAlertControllerLeftAligned( UIAlertController* avc )
{
    NSMutableParagraphStyle *paraStyle = [[[NSMutableParagraphStyle alloc] init] autorelease];
    paraStyle.alignment = NSTextAlignmentLeft;
    NSMutableAttributedString *atrStr =
        [[[NSMutableAttributedString alloc] initWithString:avc.message attributes:@{
             NSParagraphStyleAttributeName:paraStyle,
             NSFontAttributeName: [UIFont preferredFontForTextStyle: UIFontTextStyleFootnote],
         }]
         autorelease];
    [avc setValue:atrStr forKey:@"attributedMessage"];
}

Philistine

Answer 7

I noticed that some answers used a private API, which is not secure. I have a safer and simpler approach to achieve the same goal. Here is the code:

public extension UIAlertController {

    func demo() {
        title = "My Title"
        message = "My subtitle\nsecond line\nthird line"
        let messageLabel = findMessageLabel()
        messageLabel?.textAlignment = .left
    }

    func findMessageLabel() -> UILabel? {
        let originMessage = self.message
        let secret = UUID().uuidString
        self.message = secret
        let resultLabel = findMessageLabel(in: view, secret: secret)
        self.message = originMessage
        return resultLabel
    }

    private func findMessageLabel(in targetView: UIView, secret: String) -> UILabel? {
        if let label = targetView as? UILabel, label.text == secret {
            return label
        }
        for subview in targetView.subviews {
            if let label = findMessageLabel(in: subview, secret: secret) {
                return label
            }
        }
        return nil
    }

}

Smokestack

Answer 8

This property exposes the text fields, so could probably be used to configure them:

textFields

The array of text fields displayed by the alert. (read-only)

Declaration

SWIFT

var textFields: [AnyObject]? { get }

OBJECTIVE-C

@property(nonatomic, readonly) NSArray *textFields

Discussion

Use this property to access the text fields displayed by the alert. The text fields are in the order in which you added them to the alert controller. This order also corresponds to the order in which they are displayed in the alert.

Note: even though it says the property is readonly, it returns an array of text field object references which can be used to modify the controls.

Natelson

Aren't those just the UITextFields that you can add to the UIAlertController? I only display a text through the message property that is styled as a bullet list and thus would benefit from being left aligned. – Draggle

@DominikKaisers Yeah you are right; perhaps you can use the text fields and not use the message property? – Natelson

Yeah, that probably would be a workaround. I'll give it a try, if nobody has an easier way. – Draggle

These are the text input fields, not the message. – Portiere

Answer 9

yourAlertController.messageLabel.textAlignment = NSTextAlignmentLeft;

Acima

Please add explanation around your code. So that OP and future reader can easily understand your answer. – Ewer