Re: iOS: Using AppDelegate as an app-wide singleton
Re: iOS: Using AppDelegate as an app-wide singleton
- Subject: Re: iOS: Using AppDelegate as an app-wide singleton
- From: Carl Hoefs <email@hidden>
- Date: Tue, 01 Dec 2015 17:20:15 -0700
The following seems to be working out for me.
#import "AppCommon.h"
@implementation AppCommon
+ (AppCommon *)shared
{
static AppCommon *shared = nil;
static dispatch_once_t token;
dispatch_once(&token, ^{
shared = [[self alloc] init];
});
return shared;
}
-Carl
> On Dec 1, 2015, at 4:55 PM, Quincey Morris <email@hidden> wrote:
>
> On Dec 1, 2015, at 12:58 , Carl Hoefs <email@hidden <mailto:email@hidden>> wrote:
>
>> available to all classes via [[UIApplication sharedApplication] delegate].
>
>> Are there any drawbacks to this?
>
> I don’t find this practice very objectionable, but the drawback is that '[[UIApplication sharedApplication] delegate]’ has the wrong class, so you usually end up writing some sort of global function to get it pre-cast.
>
> In that case, you may as well use a different object, make it a local static variable in a class implementation, and write a static method (“[MyContextCache sharedContextCache]”) to get it. Don’t forget to use dispatch_once to create the singleton. You may not have any thread safety concerns right now, but you might easily do so later.
>
>
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