You can use the iOS Photos app to fix typical problems with colour, tone and composition. This lets you shoot and edit wherever you happen to be. However, there are some tools in the desktop version of Photos that give you more control over adjustments. Both versions of Photos have Warmth and Tint sliders, so you can remove colour casts, but the macOS version has the edge thanks to the an eyedropper that samples areas that should be white and then warms up or cools down colour casts more accurately. You can also edit colours more creatively using macOS Photos. However, the iOS version does have some tools that are missing in macOS. By using the unique tools in both versions you can perform a wide range of edits.