In iOS apps, are Cocoa and Objective-C used to code the UI?

i know html , css , have created few websites in past. design , code ui, hand on developer, add in back-end coding.

i'm going try producing an*iphone app , i'm wondering if learn how code ui before else 'real' programming.

know iphone apps use cocoa , objective-c languages used create ui? if no, what's used that?

secondly, can direct me examples of code ui of ios app?

 

ui builded if don't want learn how in code, called interface builder, it's builded xcode. can drag images/views/buttons on there, , app convert xml, , loaded in when start app (all behind scenes), create basic ui, don't need know real language. create views, navigating between the, need coding experience..
encourage

 

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