UIAlertController custom font doesn't work.
The following code is a function ShowActionSheetAsync
, show ActionSheet
.
At this point, I want to change the font of ActionSheet
. I have tried several ways, but it didn't work well. Is there good solution?
public Task<bool> ShowActionSheetAsync()
{
var source = new TaskCompletionSource<bool>();
var alert = new UIAlertController
{
Title = "title"
};
alert.AddAction(UIAlertAction.Create(
"button1",
UIAlertActionStyle.Default,
_ => source.SetResult(true)));
alert.AddAction(UIAlertAction.Create(
"cancel",
UIAlertActionStyle.Cancel,
_ => source.SetResult(false)));
// [Block 1]
var viewController = UIApplication.SharedApplication.KeyWindow.RootViewController;
ViewController.PresentViewController(alert, true, delegate
{
// [Block 2]
});
// [Block 3]
return source.Task;
}
First attempt
The following code does not work properly.
UILabel.AppearanceWhenContainedIn(typeof(UIActionSheet)).Font
= UIFont.FromName(StyleResources.MediumFontName, 20);
The second attempt
The following code also does not work properly.
FindDescendantViews<UILabel>()
is a extension method for UIView
and returns all child view of appropriate type.
var labels = alert.View.FindDescendantViews<UILabel>();
foreach (var label in labels)
{
label.Font = UIFont.FromName(StyleResources.MediumFontName, 20);
}
UIAlertController
UILabels
font and color can be set via KVC using the attributedTitle
key. Use this in [Block 3]
func changeAlert(alert: UIAlertController, backgroundColor: UIColor, textColor: UIColor, buttonColor: UIColor?) {
let view = alert.view.firstSubview().firstSubview()
view.backgroundColor = backgroundColor
view.layer.cornerRadius = 10.0
// set color to UILabel font
setSubviewLabelsToTextColor(textColor, view: view)
// set font to alert via KVC, otherwise it'll get overwritten
let titleAttributed = NSMutableAttributedString(
string: alert.title!,
attributes: [NSFontAttributeName:UIFont.boldSystemFontOfSize(17)])
alert.setValue(titleAttributed, forKey: "attributedTitle")
let messageAttributed = NSMutableAttributedString(
string: alert.message!,
attributes: [NSFontAttributeName:UIFont.systemFontOfSize(13)])
alert.setValue(messageAttributed, forKey: "attributedMessage")
// set the buttons to non-blue, if we have buttons
if let buttonColor = buttonColor {
alert.view.tintColor = buttonColor
}
}
func setSubviewLabelsToTextColor(textColor: UIColor, view:UIView) {
for subview in view.subviews {
if let label = subview as? UILabel {
label.textColor = textColor
} else {
setSubviewLabelsToTextColor(textColor, view: subview)
}
}
}
It's not allowed to either subclass or change default things of an UIAlertController. You need to make a custom view for it.
I have the solution here. I created a custom AlertThemeConfigurator that recursively runs through all the subviews looking for UILabels, then sets the themed attributedText on them for the title, message, and different types of actions. Feel free to style the attributed strings appropriately.
class AlertThemeConfigurator {
class func configureAlertViewController(alertController : UIAlertController) {
AlertLabelConfigurator.adjustLabels(inView: alertController.view, alertController: alertController)
}
class AlertLabelConfigurator {
class func adjustLabels(inView view : UIView, alertController : UIAlertController) {
for subview in view.subviews {
if subview is UILabel {
adjustLabel((subview as! UILabel), inAlertViewController : alertController)
}
adjustLabels(inView :subview, alertController : alertController)
}
}
class func adjustLabel(label : UILabel, inAlertViewController alertController : UIAlertController) {
if label.text == alertController.title {
label.attributedText = attributedTitle(label.text!)
} else if label.text == alertController.message {
label.attributedText = attributedBody(label.text!)
}
for action in alertController.actions {
if label.text == action.title {
switch action.style {
case .Default:
label.attributedText = attributedDefaultAction(action.title!)
case .Cancel:
label.attributedText = attributedCancelAction(action.title!)
case .Destructive:
label.attributedText = attributedDestructiveAction(action.title!)
}
}
}
}
class func attributedTitle(title : String) -> NSAttributedString {
let attributes = [NSFontAttributeName:UIFont(name: "Avenir-Medium", size: 20)!, NSForegroundColorAttributeName : UIColor.greenColor()]
return NSAttributedString(string: title, attributes: attributes)
}
class func attributedBody(title : String) -> NSAttributedString {
let attributes = [NSFontAttributeName:UIFont(name: "Avenir-Medium", size: 12)!, NSForegroundColorAttributeName : UIColor.orangeColor()]
return NSAttributedString(string: title, attributes: attributes)
}
class func attributedDefaultAction(title : String) -> NSAttributedString {
let attributes = [NSFontAttributeName:UIFont(name: "Avenir-Medium", size: 14)!, NSForegroundColorAttributeName : UIColor.yellowColor()]
return NSAttributedString(string: title, attributes: attributes)
}
class func attributedCancelAction(title : String) -> NSAttributedString {
let attributes = [NSFontAttributeName:UIFont(name: "Avenir-Medium", size: 14)!, NSForegroundColorAttributeName : UIColor.purpleColor()]
return NSAttributedString(string: title, attributes: attributes)
}
class func attributedDestructiveAction(title : String) -> NSAttributedString {
let attributes = [NSFontAttributeName:UIFont(name: "Avenir-Medium", size: 14)!, NSForegroundColorAttributeName : UIColor.redColor()]
return NSAttributedString(string: title, attributes: attributes)
}
}
}
To present it call
let alert = CustomAlertController(title: "Title", message:"Message" , preferredStyle: UIAlertControllerStyle.ActionSheet)
alert.addAction(UIAlertAction(title: "Close", style: UIAlertActionStyle.Default, handler: nil))
presentViewController(alert, animated: true, completion: nil)
AlertThemeConfigurator.configureAlertViewController(alert)