Recommended wording for iOS singleton mode (reprint)

1+(instancetype) shareduserloginmodel{2  3     StaticYlwuserloginmodel *instance;4     5     Staticdispatch_once_t Oncetoken;6     7Dispatch_once (&oncetoken, ^{8         9Instance =[[Ylwuserloginmodel alloc]init];Ten          One     }); A     returninstance; -      -}

The benefits of this notation are:

1. Thread safety.

2. Meet the requirements of the static analyzer.

3. Compatible with ARC

Summary: 1. This method can be used to create a singleton or some initialization action, to ensure its uniqueness. 2. This method is thread-safe, so be sure to use it boldly in a child thread. (If your dispatch_once_t *predicate object must be a global or static object.) This is important, and if this is not guaranteed, there is no guarantee that the method will only be executed once. ）

Transferred from: http://www.lrdup.net/archives/1034

Recommended wording for iOS singleton mode (reprint)