NSString initWithFormat arguments example ios

[NSString initWithFormat arguments]

Returns an NSString object initialized by using a given format string as a template into which the remaining argument values are substituted according to the user’s default locale.

- (id)initWithFormat:(NSString *)format arguments:(va_list)argList

Parameters

format

A format string. See “Formatting String Objects” for examples of how to use this method, and “String Format Specifiers” for a list of format specifiers. This value must not be nil.[NSString initWithFormat arguments]

Important: Raises an NSInvalidArgumentException if format is nil.

argList

A list of arguments to substitute into format.

Return Value of [NSString initWithFormat arguments]

An NSString object initialized by using format as a template into which the values inargList are substituted according to the user’s default locale. The returned object may be different from the original receiver.

Discussion

Invokes initWithFormat:locale:arguments: with nil as the locale.

[NSString initWithFormat arguments] example

void print (NSString *format, ...) {
    va_list args;
    va_start(args, format);

    fputs([[[[NSString alloc] initWithFormat:format arguments:args] autorelease] UTF8String], stdout);

    va_end(args);
}

[NSString initWithFormat arguments] example

NSString* format = @"Item %s and Item %s"; // Retrieved elsewhere
NSArray* args = [NSArray arrayWithObjects:@"1", @"2", nil]; // Retrieved elsewhere

// http://cocoawithlove.com/2009/05/variable-argument-lists-in-cocoa.html
char* argsList = (char*) malloc(sizeof(NSString*) * args.count);
[args getObjects:(id*) argsList];
NSString* message = [[[NSString alloc] initWithFormat:format arguments:argsList] autorelease];
free(argsList);

[NSString initWithFormat arguments] example

void log(NSString* format, ...)
{
    va_list arguments;
    va_start(list, format);

    // impossible:
    // NSString* formattedString = [[NSString alloc] initWithFormat: ???];

    // possible
    va_list argsCopy;
    va_copy(list);
    NSString* formattedString = [[NSString alloc] initWithFormat:format arguments:argsCopy];    

    // do something cool with your string
    NSLog(@"%@", formattedString);
    va_end(argsCopy);
    va_end(list);
}