How to append int value to string?

stringByAppendingFormat: returns the new string, it does not modify the receiver string. That's why you are getting no change. Try this:

NSMutableString  *selectDay=@"Wed 14 May";
NSString *newString = [selectDay stringByAppendingFormat:@"%i", yearNumber];
NSLog(@"%@", newString);

Or this:

NSMutableString  *selectDay=@"Wed 14 May";
NSString *newString = [NSString stringWithFormat:@"%@%i", selectDay, yearNumber];
NSLog(@"%@", newString);

EDIT: Actually you don't need mutable string for this. selectDay should be a normal NSString.

NSString  *selectDay=@"Wed 14 May";

change the below line

[selectDay stringByAppendingFormat:@"%i", yearNumber];

to

selectDay = [NSString stringWithFormat:@"%@%i", selectDay, yearNumber];

definitely it will work ...

You define your variable to be of type NSMutableString *, but the constant string you're passing is of type NSString * which is already wrong. There are two solutions: with or without NSMutableString.

NSMutableString *selectDay = [NSMutableString stringWithString:@"Wed 14 May"];
[selectDay appendFormat:@"%i", yearNumber];
NSLog(@"%@", selectDay);

Here the mutable string is generated from the constant string and then it is modified through appending.

NSString *selectDay = @"Wed 14 May";
NSString *newDay = [selectDay stringByAppendingFormat:@"%i", yearNumber];
NSLog(@"%@", newDay);

The point here is that stringByAppendingFormat: does not modify the original string, it returns a new one. And you simply need to "catch" it in a variable.

Try this:-

NSString   *selectDay=@"Wed 14 May";
    int yearNumber=2011;
    selectDay=[selectDay stringByAppendingFormat:[NSString stringWithFormat:@"%d", yearNumber]];
    NSLog(@"%@",selectDay);

   NSString *selectDay=@"Wed 14 May";
    NSString *appendedString = [NSString stringWithFormat:@"%@ %d",selectDay, yearNumber];

    NSLog(@"%@",appendedString);

Try this

You can try:

NSString *selectDay = [NSString stringWithFormat:@"Wed 14 May %d", yearNumber];