Dynamic Type with Weight-Matching

UIFontDescriptor+DynamicType.m

@implementation UIFontDescriptor (DZWDynamicType)

+ (instancetype)dzw_preferredFontDescriptorWithTextStyle:(NSString *)style {
    return [[self preferredFontDescriptorWithTextStyle:style] dzw_fontDescriptorWithMatchingFamily:@"Avenir Next"];
}

- (instancetype)dzw_fontDescriptorWithMatchingFamily:(NSString *)family {
    NSMutableDictionary *attributes = [self.fontAttributes mutableCopy];
    [attributes removeObjectForKey:UIFontDescriptorTextStyleAttribute];
    UIFontDescriptor *newDesc = (__bridge_transfer UIFontDescriptor *)CTFontDescriptorCreateCopyWithFamily((__bridge CTFontDescriptorRef)self, (__bridge CFStringRef)family);
    [attributes addEntriesFromDictionary:newDesc.fontAttributes];
    return [self.class fontDescriptorWithFontAttributes:attributes];
}

@end