How do I concatenate strings in Objective-C?

Question

Are there any shortcuts to (stringByAppendingString:) string concatenation in Objective-C or shortcuts for working with NSString or other objects in general?

e.g. I'd like to make this:

NSString *myString = @"This";
NSString *test = [myString stringByAppendingString:@" is just a test"];

something more like this:

string myString = "This";
string test = myString + " is just a test";

Answer 1

Two answers I can think of... neither is particularly as pleasant as just having a concatenation operator.

First, use an NSMutableString, which has an appendString method, removing some of the need for extra temp strings.

Second, use an NSArray to concatenate via the componentsJoinedByString method.

Answer 2

The only way to make c = [a stringByAppendingString: b] any shorter is to use autocomplete at around the st point. The + operator is part of C, which doesn't know about Objective-C objects.

Answer 3

I'm guessing you're not happy with multiple appends (a+b+c+d), in which case you could do:

NSLog(@"%@", [Util append:one, @" ", two, nil]); // "one two"
NSLog(@"%@", [Util append:three, @"/", two, @"/", one, nil]); // three/two/one

using something like

+ (NSString *) append:(id) first, ...
{
    NSString * result = @"";
    id eachArg;
    va_list alist;
    if(first)
    {
     result = [result stringByAppendingString:first];
     va_start(alist, first);
     while (eachArg = va_arg(alist, id)) 
      result = [result stringByAppendingString:eachArg];
     va_end(alist);
    }
    return result;
}

but you'd get the same result using:

[NSString stringWithFormat:@"%@/%@/%@", three, two, one];

Answer 4

NSString *label1 = @"Process Name: ";
NSString *label2 = @"Process Id: ";
NSString *processName = [[NSProcessInfo processInfo] processName];
NSString *processID = [NSString stringWithFormat:@"%d", [[NSProcessInfo processInfo] processIdentifier]];
NSString *testConcat = [NSString stringWithFormat:@"%@ %@ %@ %@", label1, processName, label2, processID];

Answer 5

Shortcut by creating AppendString (AS) macro ...

#define AS(A,B)    [(A) stringByAppendingString:(B)]

NSString *myString = @"This";

NSString *test = AS(myString,@" is just a test");

Answer 6

NSString *label1 = @"Process Name: ";
NSString *label2 = @"Process Id: ";
NSString *processName = [[NSProcessInfo processInfo] processName];
NSString *processID = [NSString stringWithFormat:@"%d", [[NSProcessInfo processInfo] processIdentifier]];
NSString *testConcat = [NSString stringWithFormat:@"%@ %@ %@ %@", label1, processName, label2, processID];

Answer 7

Use this way

NSString *string1,*string2,result;

string1 = @"This is ";
string2 = @"my string.";
result = [NSString alloc];

result = [result stringByAppendingString:string1];
result = [result stringByAppendingString:string2];
 OR

result = [result stringByAppendingString:@"This is "];
result = [result stringByAppendingString:@"my string."];