IOS _ attribute _ (warn_unused_result), attributeunused

IOS _ attribute _ (warn_unused_result), attributeunused

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Meaning of this Keyword: If a function uses this keyword, the compiler will warn you when the function is called to check or use the return value.

Usage: When Encapsulating some functions (or compiling the SDK), if the use of the return value is important, use this keyword to remind the compiler to check whether the return value is used.

Example:

-(BOOL) TestFunc :( NSInteger) num _ attribute _ (warn_unused_result) {return num> 0? YES: NO ;}

If I call

[Self TestFunc: 10];

The compiler will give the following warning:

The warning disappears after the returned value is checked.

BOOL result = [self TestFunc: 10];