[SOLVED] UIFontWeightTrait and UIFontDescriptorFamilyAttribute Ignored when creating UIFont from UIFontDescriptor

UIFontWeightTrait and UIFontDescriptorFamilyAttribute Ignored when creating UIFont from UIFontDescriptor

Given the following code and a device running iOS 7.1 or later:

 NSDictionary *fontTraitsDictionary = @{UIFontWeightTrait : @(-1.0)};
 NSDictionary *attributesDictionary = @{
                                       UIFontDescriptorFamilyAttribute : @"Helvetica Neue", 
                                       UIFontDescriptorTraitsAttribute : fontTraitsDictionary
                                       };
 UIFontDescriptor *ultraLightDescriptor = [UIFontDescriptor fontDescriptorWithFontAttributes:attributesDictionary];
 UIFont *shouldBeAnUltraLightFont = [UIFont fontWithDescriptor:ultraLightDescriptor size:24];

 NSLog(@"%@", shouldBeAnUltraLightFont);

I would expect the value of shouldBeAnUltraLightFont to be an instance of HelveticaNeue-UltraLight, but instead it is:

<UICTFont: 0x908d160> font-family: "Helvetica"; font-weight: normal; font-style: normal; font-size: 24.00pt

I am following the Apple documentation as far as I understand it. Why is the font family and font weight information completely ignored?

Things I’ve Tried

I've tried other family names like Helvetica, Avenir, etc.
I've tried other font weights in the valid range from -1 to 1, in increments of 0.25

Regardless of these changes, the font returned is always a vanilla instance of Helvetica at normal weight.

Solution

I ran into the same issue, and the documentation was not much help. Eventually I figured out that using the family attribute combined with the face attribute worked:

 UIFontDescriptor* desc = [UIFontDescriptor fontDescriptorWithFontAttributes:
        @{
            UIFontDescriptorFamilyAttribute: @"Helvetica Neue",
            UIFontDescriptorFaceAttribute: @"Light"
        }
    ];