How to align baselines of text in UILabels with different font sizes on iOS?

I was using this answer in a couple of different places, but the baselines were sometimes a pixel off on Retina displays. The snippet below accounts for the screen’s scale:

[majorLabel sizeToFit];
[minorLabel sizeToFit];

CGRect changedFrame = minorLabel.frame;
changedFrame.origin.x = CGRectGetWidth(majorLabel.frame);

const CGFloat scale = [UIScreen mainScreen].scale;
const CGFloat majorLabelBaselineInSuperView = CGRectGetMaxY(majorLabel.frame) + majorLabel.font.descender;
const CGFloat minorLabelBaselineInOwnView = CGRectGetHeight(minorLabel.frame) + minorLabel.font.descender;
changedFrame.origin.y = ceil((majorLabelBaselineInSuperView - minorLabelBaselineInOwnView) * scale) / scale;

minorLabel.frame = changedFrame;

You can get pixel-perfect baseline alignment for any pair of UILabels by using the UIFont ascender value in a simple calculation. Here's how:

[majorLabel sizeToFit];
[minorLabel sizeToFit];

CGRect changedFrame = minorLabel.frame;
changedFrame.origin.y = ceilf(majorLabel.frame.origin.y + (majorLabel.font.ascender - minorLabel.font.ascender));
minorLabel.frame = changedFrame;

ceilf() is used because the font.ascender values may be fractional.

I've tested this on both retina and non-retina devices, with excellent results. Positioning the two labels relative to each other on the x-axis has been omitted, as your needs may vary. If you need a quick explanation of what the UIFont ascender is (plus other UIFont info) check out this clear, concise article.