UIImagePNGRepresentation issues? / Images rotated by 90 degrees

I had the same problem and just figured out the reason: starting with iOS 4.0 when the camera takes a photo it does not rotate it before saving, it simply sets a rotation flag in the EXIF data of the JPEG.

If you save a UIImage as a JPEG, it will set the rotation flag.

PNGs do not support a rotation flag, so if you save a UIImage as a PNG, it will be rotated incorrectly and not have a flag set to fix it. So if you want PNGs you must rotate them yourself.

I would call this a bug in the PNG saving function but that’s just an opinion (they should at least warn you about this).

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