NSInvocation Example

NSInvocation Example

//
//  ViewController.m
//  
//
//  Created by Jonathan King on 19/08/2012.
//
//

#import "ViewController.h"

// Makes inserting arguments at an index easier to read and manage 
#define NSInvocationObjectIndex(index) index + 2

@interface ViewController ()
// Private Methods
- (void)setUpInvocations;
- (void)logThisString:(NSString *)string andThisInteger:(int)integer;
// Private Properties
@property (strong, nonatomic) NSMutableArray *mutableArray;
@end

@implementation ViewController

// Not necessary with LLVM 4.0
@synthesize mutableArray = _mutableArray;

#pragma mark View Lifecycle

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view.
    
    [self setUpInvocations];
}

- (void)viewDidUnload
{
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}


#pragma mark Instace Methods

- (void)setUpInvocations
{
    if (!_mutableArray) _mutableArray = [[NSMutableArray alloc] init];

    // Set up the NSInvocation(s)
    NSMethodSignature *loggingStringAndIntegerMethodSignature = [self methodSignatureForSelector:@selector(logThisString:andThisInteger:)];
    NSInvocation *logStringAndInteger = [NSInvocation invocationWithMethodSignature:loggingStringAndIntegerMethodSignature];    
    logStringAndInteger.selector = @selector(logThisString:andThisInteger:);
    logStringAndInteger.target = self;
    
    NSMethodSignature *addingObjectToArrayMethodSignature = [_mutableArray methodSignatureForSelector:@selector(addObject:)];
    NSInvocation *addObjectToArray = [NSInvocation invocationWithMethodSignature:addingObjectToArrayMethodSignature];
    addObjectToArray.selector = @selector(addObject:);
    addObjectToArray.target = _mutableArray;
    
    // Variables that will be included in the invocations
    NSString *stringThatWillBeLogged = @"Twenty Five";
    int integerThatWillBeLogged = 5;
    NSString *stringthatWillBeAddedToTheArray = @"Array String";
    
    // Set the arguments of the NSInvocation(s)
    [logStringAndInteger setArgument:&stringThatWillBeLogged atIndex:NSInvocationObjectIndex(0)];
    [logStringAndInteger setArgument:&integerThatWillBeLogged atIndex:NSInvocationObjectIndex(1)];
    [addObjectToArray setArgument:&stringthatWillBeAddedToTheArray atIndex:NSInvocationObjectIndex(0)];
    
    // Invoke and schedule the NSInvocation(s)
    [logStringAndInteger invoke];
    [NSTimer scheduledTimerWithTimeInterval:2.0f invocation:logStringAndInteger repeats:YES];
    [addObjectToArray invoke];
    [NSTimer scheduledTimerWithTimeInterval:2.0f invocation:addObjectToArray repeats:YES];
    
}

- (void)logThisString:(NSString *)string andThisInteger:(int)integer
{    
    NSLog(@"String: %@ \n Integer: %d \n \n", string, integer);
}

@end