What are pixels and points in iOS?

Question

from UIImage reference:

@property(nonatomic, readonly) CGSize size

The dimensions of the image, taking orientation into account.

Answer 1

Using data from http://www.paintcodeapp.com/news/ultimate-guide-to-iphone-resolutions I set up the formula sqrt(pointWidth^2+pointHeight^2)/diagonalInches to figure out how many points each phone displayed per inch.

Results:

• iPhone 2G, 3G, 3GS, 4, 4s = 164.825201164068082 Points Per Inch

• iPhone 5, 5s = 162.9846618550346903

• iPhone 6 = 162.8061416117083255

• iPhone 6 Plus = 153.535954278463216

As you can tell a point is roughly the same size on each phone. Using the same webopage, you can set up the same formula with the pixel values, and you'll notice large irregularities due to higher pixel densities on the newer phones.