iOS concatenate string stringWithFormat

Hello!


to concatenate the string with a wriiten text
(here Hello world )
and a value existing in the code
we usually use this
myLabel.text= [NSString stringWithFormat"Hello world ", myString];

But now if i have two values existing in the code e.g. inforesult and myString how can i concatenate them together ?

i tried
myLabel.text= [NSString stringWithFormat: inforesult, myString];

but it doesn't work. Returns me only the inforesult value displayed.

How can i solve this?

while searching i also got
NSString *string1= Inforesultat;
NSString *string2 = myString;
string1 = [string1 stringByAppendingString:string2];


I wonder what is the difference and which one is better to use?