Font Descriptor returns nil in iOS 8

The following code works fine in iOS 7, but doesn't return bold or italic font in iOS 8. It is ok for Helvetica Neue, but doesn't work for Arial font.

UIFontDescriptor *descriptor1 = [UIFontDescriptor fontDescriptorWithFontAttributes:@{UIFontDescriptorFamilyAttribute: @"Arial"}];
UIFontDescriptor* boldFontDescriptor1 = [descriptor1 fontDescriptorWithSymbolicTraits:UIFontDescriptorTraitBold];
UIFont* font1 = [UIFont fontWithDescriptor:boldFontDescriptor1 size:16.0];
[self.lblArialB setFont:font1];

Tested on device and simulator and still same error.

FWIW, this is the workaround I came up with, using UIFontDescriptor's attributes dictionary initializer instead of the seemingly buggy fontDescriptorWithSymbolicTraits:

NSString *fontFamily = @"Arial";
BOOL isBold = YES;
BOOL isItalic = YES;
CGFloat fontSize = 20.0;
UIFontDescriptor *fontDescriptor = [UIFontDescriptor fontDescriptorWithFontAttributes:
                  @{
                    @"NSFontFamilyAttribute" : fontFamily,
                    @"NSFontFaceAttribute" : (isBold && isItalic ? @"Bold Italic" : (isBold ? @"Bold" : (isItalic ? @"Italic" : @"Regular")))
                    }];
UIFont *font = [UIFont fontWithDescriptor:fontDescriptor size:fontSize];