I want to filter my table result with 4 different tabs at the top of the page. All I could find is apps that are using max 3 (kayak, safari) or min 2 obviously. Is this ok to design 4 for ios app? is there a rule limiting me to just 3?
Old iPhone interface guidelines set the minimum touch target size at 44 pixels, or about 7mm on the 320x480 screens. But most interface guidelines nowadays state a minimum of 9x9 mm, or 7x7 with 1mm whitespace (creating a 2mm gap, and you still end up at 9mm accuracy).
For the 58mm wide iPhone 6 screen, this means you can fit in 6.4444 button widths. Or, you know… 6 buttons.
However, finger tips are significantly smaller than our finger pads. The full width of the finger is about 2 cm wide, maybe 1 inch. But the pad, the part that gets flattened on the screen, is somewhere from 10 to 15 mm. For this reason, you might want to limit yourself to only 4 buttons.
So in short, yes you can use 4 tabs. You can even use more. But always ask yourself: “Does this tab add enough value?” Not just to offset the less accurate buttons, but also the added effort of tab switching and task switching. How similar is the content of the tabs? Can you maybe put two under one tab?
For example: you could have tabs for product images, videos and description, but you could also have one overview tab that has a caroussel at the top for videos and images, and underneath that the text description. Scrolling costs less effort than tab switching, and there’s even a decent chance both the carousell and a (short) text can fit on a single screen.
Apple's "iOS Human Interface Guidelines" (not really a rulebook, but a good reference for what's ok in iOS) suggest, you should consider 5 or less segments (that control you refer to is called "Segmented Controls"), so using 4 shouldn't be something out of the ordinary. Just remeber that with fewer choices, the usability is better.