if you have an iPhone, you have everything to be able to take and print high resolution pictures.
Apple Photo App will store your pictures, allow you to edit them and send them off to a printer or a site that produces photo books.
Apple stopped their Photo Book program not long ago but there are a number of sites that offer the same sort of thing.
Remember, you can always lower the resolution of photo's you have taken but you cannot increase it easily
Make photo books with photos from phone. What is the best way to get high resolutions for printing at little or no cost. What software is available?