Re: MKAnnotation coordinate
Re: MKAnnotation coordinate
- Subject: Re: MKAnnotation coordinate
- From: Fritz Anderson <email@hidden>
- Date: Tue, 9 Nov 2010 09:18:22 -0600
On 9 Nov 2010, at 3:31 AM, Dan Hopwood wrote:
> Ok so I am working with MKAnnotations on my map view and want to know the *
> correct* (i.e. the Apple intended) way to set up my custom annotation class
> so that I can set the coordinate upon initialisation but also access the
> coordinate attribute from outside the class e.g. in my case I wish to do
> something like:
>
> region.center = myAnnotation.coordinate;
>
> The above gives me an error and says the assignment is between incompatible
> types.
We need something better than "something like." Assuming "region" is an MKCoordinateRegion, and "myAnnotation" implements MKAnnotation, the above line is okay. But if "region" is your shorthand for "someMapView.region", you have a problem. Show us the code.
> I've done plenty of googling and have seen a few different solutions but
> none of which seemed to allow me to access the coordinate. Some people
> define a coordinate member variable and then @property/synthesize.
> Others named the member variable _coordinate and then *just* synthesized it
> (not @property) using @synthesize _coordinate = coordinate; - I don't fully
> understand what that means. Finally (in the case of the MapCallouts source)
> others have defined a function called coordinate that returns the
> coordinate.
<MKAnnotation> already declares @property coordinate, so there is no reason to re-declare it. A -coordinate method, or a @synthesize if there is a "coordinate" instance variable to back it, is enough.
> If someone could give tell me the correct solution by means of a really
> simple example i.e. what should go in the .h and .m (I'm only interested in
> the coordinate attribute for now) and then how to correctly access the
> coordinate attribute from outside the class for assignment e.g. the center
> attribute of the region object (sorry I can't remember the exact name).
Don't do this by Braille from what I can tell you off the top of my head, or from cookbook examples. Read and understand for yourself the documentation on properties at <http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/ObjectiveC/Articles/ocProperties.html>.
— F
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