UIAlertController custom font, size, color

Question

I am using new UIAlertController for showing alerts. I have this code:

// nil titles break alert interface on iOS 8.0, so we'll be using empty strings
UIAlertController *alert = [UIAlertController alertControllerWithTitle: title == nil ? @"": title message: message preferredStyle: UIAlertControllerStyleAlert];


UIAlertAction *defaultAction = [UIAlertAction actionWithTitle: cancelButtonTitle style: UIAlertActionStyleCancel handler: nil];

[alert addAction: defaultAction];

UIViewController *rootViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
[rootViewController presentViewController:alert animated:YES completion:nil];

Now I want to change title and message font, color, size and so. What's best way to do this?

Edit: I should insert whole code. I created category for UIView that I could show right alert for iOS version.

@implementation UIView (AlertCompatibility)

+( void )showSimpleAlertWithTitle:( NSString * )title
                          message:( NSString * )message
                cancelButtonTitle:( NSString * )cancelButtonTitle
{
    float iOSVersion = [[UIDevice currentDevice].systemVersion floatValue];
    if (iOSVersion < 8.0f)
    {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle: title
                                                        message: message
                                                       delegate: nil
                                              cancelButtonTitle: cancelButtonTitle
                                              otherButtonTitles: nil];
        [alert show];
    }
    else
    {
        // nil titles break alert interface on iOS 8.0, so we'll be using empty strings
        UIAlertController *alert = [UIAlertController alertControllerWithTitle: title == nil ? @"": title
                                                                       message: message
                                                                preferredStyle: UIAlertControllerStyleAlert];


        UIAlertAction *defaultAction = [UIAlertAction actionWithTitle: cancelButtonTitle
                                                                style: UIAlertActionStyleCancel
                                                              handler: nil];

        [alert addAction: defaultAction];

        UIViewController *rootViewController = [UIApplication sharedApplication].keyWindow.rootViewController;
        [rootViewController presentViewController:alert animated:YES completion:nil];
    }
}

Answer 1

Use UIAppearance protocol. Example for setting a font - create a category to extend UILabel:

@interface UILabel (FontAppearance)
@property (nonatomic, copy) UIFont * appearanceFont UI_APPEARANCE_SELECTOR;
@end


@implementation UILabel (FontAppearance)

-(void)setAppearanceFont:(UIFont *)font {
    if (font)
        [self setFont:font];
}

-(UIFont *)appearanceFont {
    return self.font;
}

@end

And its usage:

UILabel * appearanceLabel = [UILabel appearanceWhenContainedIn:UIAlertController.class, nil];
[appearanceLabel setAppearanceFont:[UIFont boldSystemFontOfSize:10]]; //for example

Tested and working with style UIAlertControllerStyleActionSheet, but I guess it will work with UIAlertControllerStyleAlert too.

P.S. Better check for class availability instead of iOS version:

if ([UIAlertController class]) {
    // UIAlertController code (iOS 8)
} else {
    // UIAlertView code (pre iOS 8)
}

Answer 2

I'm using it.

[[UIView appearanceWhenContainedIn:[UIAlertController class], nil] setTintColor:[UIColor blueColor]];

Add one line (AppDelegate) and works for all UIAlertController.

Answer 3

Swift 4

Example of custom font on the title. Same things for other components such as message or actions.

    let titleAttributed = NSMutableAttributedString(
            string: Constant.Strings.cancelAbsence, 
            attributes: [NSAttributedStringKey.font:UIFont(name:"FONT_NAME",size: FONT_SIZE)]
    )

    let alertController = UIAlertController(
        title: "",
        message: "",
        preferredStyle: UIAlertControllerStyle.YOUR_STYLE
    )

    alertController.setValue(titleAttributed, forKey : "attributedTitle")
    present(alertController, animated: true, completion: nil)

Answer 4

There is a problem with setting the tint color on the view after presenting; even if you do it in the completion block of presentViewController:animated:completion:, it causes a flicker effect on the color of the button titles. This is sloppy, unprofessional and completely unacceptable.

Other solutions presented depend on the view hierarchy remaining static, something that Apple is loathe to do. Expect those solutions to fail in future releases of iOS.

The one sure-fire way to solve this problem and to do it everywhere, is via adding a category to UIAlertController and swizzling the viewWillAppear.

The header:

//
//  UIAlertController+iOS9TintFix.h
//
//  Created by Flor, Daniel J on 11/2/15.
//

#import <UIKit/UIKit.h>

@interface UIAlertController (iOS9TintFix)

+ (void)tintFix;

- (void)swizzledViewWillAppear:(BOOL)animated;

@end

The implementation:

//
//  UIAlertController+iOS9TintFix.m
//
//  Created by Flor, Daniel J on 11/2/15.
//

#import "UIAlertController+iOS9TintFix.h"
#import <objc/runtime.h>

@implementation UIAlertController (iOS9TintFix)

+ (void)tintFix {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        Method method  = class_getInstanceMethod(self, @selector(viewWillAppear:));
        Method swizzle = class_getInstanceMethod(self, @selector(swizzledViewWillAppear:));
        method_exchangeImplementations(method, swizzle);});
}

- (void)swizzledViewWillAppear:(BOOL)animated {
    [self swizzledViewWillAppear:animated];
    for (UIView *view in self.view.subviews) {
        if (view.tintColor == self.view.tintColor) {
            //only do those that match the main view, so we don't strip the red-tint from destructive buttons.
            self.view.tintColor = [UIColor colorWithRed:0.0 green:122.0/255.0 blue:1.0 alpha:1.0];
            [view setNeedsDisplay];
        }
    }
}

@end

Add a .pch (precompiled header) to your project and include the category:

#import "UIAlertController+iOS9TintFix.h"

Make sure you register your pch in the project properly, and it will include the category methods in every class that uses the UIAlertController.

Then, in your app delegates didFinishLaunchingWithOptions method, import your category and call

[UIAlertController tintFix];

and it will automatically propagate to every single instance of UIAlertController within your app, whether launched by your code or anyone else's.

This solution works for both iOS 8.X and iOS 9.X and lacks the flicker of the tint change post-presentation approach. It is also completely agnostic with respect to the view hierarchy of the sub-views of the UIAlertController.

Happy hacking!

Answer 5

You can change color of button text using this code:

alertC.view.tintColor = your color;

Maybe this will help you.

Answer 6

Use UIAppearance protocol. Do more hacks with appearanceFont to change font for UIAlertAction.

Create a category for UILabel

UILabel+FontAppearance.h

@interface UILabel (FontAppearance)

@property (nonatomic, copy) UIFont * appearanceFont UI_APPEARANCE_SELECTOR;

@end

UILabel+FontAppearance.m

@implementation UILabel (FontAppearance)

- (void)setAppearanceFont:(UIFont *)font
{
    if (self.tag == 1001) {
        return;
    }

    BOOL isBold = (self.font.fontDescriptor.symbolicTraits & UIFontDescriptorTraitBold);
    const CGFloat* colors = CGColorGetComponents(self.textColor.CGColor);

    if (self.font.pointSize == 14) {
        // set font for UIAlertController title
        self.font = [UIFont systemFontOfSize:11];
    } else if (self.font.pointSize == 13) {
        // set font for UIAlertController message
        self.font = [UIFont systemFontOfSize:11];
    } else if (isBold) {
        // set font for UIAlertAction with UIAlertActionStyleCancel
        self.font = [UIFont systemFontOfSize:12];
    } else if ((*colors) == 1) {
        // set font for UIAlertAction with UIAlertActionStyleDestructive
        self.font = [UIFont systemFontOfSize:13];
    } else {
        // set font for UIAlertAction with UIAlertActionStyleDefault
        self.font = [UIFont systemFontOfSize:14];
    }
    self.tag = 1001;
}

- (UIFont *)appearanceFont
{
    return self.font;
}

@end

Usage:

add

[[UILabel appearanceWhenContainedIn:UIAlertController.class, nil] setAppearanceFont:nil];

in AppDelegate.m to make it work for all UIAlertController.