尝试从NSInvocation获取NSString类型参数时发出警告

Question

I want to get argument passed in, I already got the NSInvocation instance. I tried:

NSString *firstArg;
[invocation getArgument:&firstArg atIndex:2];// Warning here.

But I got warning:

How to get rid of it?

Answer 1

getArgument requires Nonnull , you have not initialized your NSString so,

change your code as below:

NSString *firstArg=nil;
[invocation getArgument:&firstArg atIndex:2];