CGFloat is a word-size agnostic way to express a floating point number (on 32 bit devices, it’s a float. On 64 bit devices, it’s a double).
CGFloat.leastNormalMagnitude is effectively the same as
DBL_MIN, depending on the device). It is less than or equal to all positive “normal” numbers. Subnormal means that “they are represented with less precision than normal numbers”. Note that zeros and negative numbers are also less than