The phrase "affinity for it" is correct and usable in written English.
You can use it to express a natural liking or attraction to something.
Example: "She has an affinity for it, often spending hours immersed in the subject."
Alternatives: "liking for it" or "fondness for it".
Though the White House press secretary has insisted that "the executive office of the president is not participating in a pilot programme" to replace Obama's BlackBerry, it might only be a matter of time – though if Hillary Clinton succeeds him, her well-known affinity for it could extend its survival just a little longer.
The longer I'd been away from the South, the more I had an affinity for it.
I had a natural affinity for it, I think, so it wasn't like a conscious thing or anything like that.
Ms. DiPietro, 27, who is originally from Maplewood, N.J., "developed an affinity for it, too".
I know both Shoals and I share an affinity for it.
When Pat Boone covered Little Richard, you think, 'Huh?', he's got no affinity for it.
Since 1-EBIO opens KCa3.1 in resting cells by increasing its affinity for Ca2+ 35, it is particularly interesting that adenosine closes KCa3.1 under these conditions.
However, if your rabbit has not exhibited an affinity for water, it's best not to risk getting it wet.
I didn't have much affinity for volleyball; it wrecked my elbow.
Given Diana's affinity for children, it was not surprising that they were greatly affected.
Meanwhile, America First is drawing a fan club of supporters in the orbits of cable news punditry, social media and former Trump aides and surrogates — united by their adoration of the president and affinity for expressing it on Instagram.
