objective c - Xcode iPad storyboard -


so i'm looking @ ipad objective-c xcode project's source code , new , having trouble figuring out what's going on.

so i'm looking @ file mainstoryboard_ipad.storyboard shows various buttons , things displayed on actual ipad screen.

how "link up" each of these graphical buttons method when click particular button? there 2 other files in program _.h/m seem include methods relate buttons don't see how exactly.

can here explain process or show me link (very clear , understandable) guide?

yeah, in 1 of key questions had myself before spending hours in tutorials. dont't think documented experienced programmers dive app development.

the usual way declare property of type of object (ie. uibutton) within .h file of related view controller class (a uiviewcontroller subclass or uitableviewcontroller respectively). key add keyword iboutlet it.

the keyword enables interface builder (ib; storyboard editor) identify properties supposed linked ui items created , maintained within ib. link reference outlet dragging line connections inspector (right hand pane in ib view, right icon on tab bar of pane, 1 arrow in circle) actual object either in preview (center pane) or in view hierarchy view.

within .h file (and within .m file if synthesize there) connection acknowledged dot in circle left of declaration. empty circle when property not connected. there no circle @ when property not marked iboutlet.

now, when access property within (or without - possible not recommended) view controller, should different nil in methods (viewdidload , follwonig methods). can or set values , setting them change related ui item on screen.

a lot of ui items controls (subclasses of uicontrol, uibutton instance) , have actions assigned. calling action control sends message controller, user did of interest. user may have changed value of uiswitch or pressed uibutton. pretty similar properties. declare method. no need doing in .h more still follow pattern. start typing - (ibaction) somename , autocompletion guide through. can see (ibaction) synonyme (void), tells xcode ide supposed linked control action. ibactions receive 1 parameter of type (id) or (uiview) or (uicontrol). (i not quite sure actual type). key receives reference control instance on action performed - sender. typical pattern: 

-(ibaction) mybuttonwaspressed:(uibutton *)sender;

you can write books whether wise typcast uibutton @ stage or not. however, works should test within method , make sure uibutton (eg. using iskindofclass:[uibutton class]) before access property or method unique uibuttons. if react on ibaction beeing invoked , don't acces sender @ all, may ignore sender or omit parameter. think following should work too: -(ibaction) mybuttonwaspressed;

of course need implement method in .m file.

you link action control in similar way property dragging line within ib. in case of button asked assign event. buttons touchupinside event not bad choice. assin same action number of events if find have reasons doing so. (can't think of reason, works nicely).


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