Demo crashes on iOS 6

[wangyandongnx]

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'NSConcreteMutableAttributedString addAttribute:value:range:: nil value' as - [ASValuePopUpView setTextColor:] and - [ASValuePopUpView setFont:] do not handle nil value.

- (void)setFont:(UIFont *)font
{
    [_attributedString addAttribute:NSFontAttributeName
                                  value:font
                                  range:NSMakeRange(0, [_attributedString length])];
}

==>

- (void)setFont:(UIFont *)font
{
    if (nil != font)
    {
        [_attributedString addAttribute:NSFontAttributeName
                                  value:font
                                  range:NSMakeRange(0, [_attributedString length])];
    }
    else
    {
        // Or use a default font settings ???
        [_attributedString removeAttribute:NSFontAttributeName range:NSMakeRange(0, [_attributedString length])];
    }
}

[alskipp]

Thanks for raising the issue. The problem is caused by the use of the font Menlo-Bold in the demo app. Menlo-Bold isn't available on iOS6 so [UIFont fontWithName:@"Menlo-Bold" size:22] returns nil.

[alskipp]

I've adjusted the demo app to use a font which is available on iOS6. Instead of handling a nil value I've decided to explicitly assert that the font can not be nil in - (void)setFont:(UIFont *)font.

NSAssert(font, @"font can not be nil, it must be a valid UIFont");

I think there's a danger of causing more confusion by using a default font when receiving a nil argument. For example if someone misspells the name of a font in UIFont fontWithName: they will get the default font, instead of the one they were expecting. If an exception is raised the misspelling will be much easier to discover.