madewulf madewulf - 5 months ago 26
iOS Question

Typesetting a font in small caps on iOS

On iOS, I load a custom font in my project by adding its file name (an .otf file) to the info.plist file and then using this line of code:


UIFont myFont * = [UIFont fontWithName:titleFontName size:titleFontSize];


I obtain the font that I can use in UILabels and UITextViews.

How could I obtain that this font is displayed only in small caps? If I use it in Photoshop, it's possible to turn on the small caps switch to have all words typeset in small caps (and so, I conclude that there is nothing missing with the font). How could I obtain a similar effect on iOS?

Converting my strings to uppercase is not a viable option for other reasons.

Further information : the font has only one member in its family, as I could understand by using the following code, there is no standalone small caps member in the family.

for (NSString * familyName in [UIFont familyNames]) {

NSLog(@"---------------- %@ ---------------", familyName);
for (NSString * fontName in[UIFont fontNamesForFamilyName:familyName] )
NSLog(@"- %@", fontName);
}

Answer

Small caps are enabled in the font through an open type feature. In iOS 7 we can use a font descriptor to access open type features and enable small caps.

This question goes into how to turn on small caps using core text, but the same can be done for UIFonts and UIKit views just as easily. You'll need to create a UIFontDescriptor and set the UIFontDescriptorFeatureSettingsAttribute to an array of dictionaries for the features you want to enable.

Each font feature dictionary contains a key and value to specify the feature type, and a key and value for the feature selector. Depending on the font you're using, you'll need to find the correct values corresponding to small caps. You can find these in the array that the commented section logs.

UIFont Category

This category will generate a UIFont object with small caps enabled. You'll need to add the correct font name.

#import "UIFont+SmallCaps.h"
#import <CoreText/CoreText.h>

@implementation UIFont (SmallCaps)

+ (UIFont *) applicationSmallCapsFontWithSize:(CGFloat) size {
    /*
    // Use this to log all of the properties for a particular font
    UIFont *font = [UIFont fontWithName: fontName size: fontSize];
    CFArrayRef  fontProperties  =  CTFontCopyFeatures ( ( __bridge CTFontRef ) font ) ;
    NSLog(@"properties = %@", fontProperties);
    */

    NSArray *fontFeatureSettings = @[ @{ UIFontFeatureTypeIdentifierKey: @(kLowerCaseType),
                                         UIFontFeatureSelectorIdentifierKey : @(kLowerCaseSmallCapsSelector) } ];

    NSDictionary *fontAttributes = @{ UIFontDescriptorFeatureSettingsAttribute: fontFeatureSettings ,
                                      UIFontDescriptorNameAttribute: FONT_NAME } ;

    UIFontDescriptor *fontDescriptor = [ [UIFontDescriptor alloc] initWithFontAttributes: fontAttributes ];

    return [UIFont fontWithDescriptor:fontDescriptor size:size];
}

@end
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