Descompactando arquivos no iOS usando a classe ZipArchive

Sample.m

#import "ViewController.h"
#import "ZipArchive.h"

@interface ViewController ()
- (IBAction)unzip:(id)sender;
@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
	// Do any additional setup after loading the view, typically from a nib.
}

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


- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
	return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);
}

#pragma mark - Private Methods

- (IBAction)unzip:(id)sender {
	ZipArchive *zip = [ZipArchive new];
	
	//define aonde o arquivo será extraído
	//nesse caso ficará dentro de Documents/files/
	NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
        NSString *documentsDirectory = [paths objectAtIndex:0];
        NSString *path = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"files/"]];
	
	//arquivo a ser extraído
	NSString *filePath = [[NSBundle mainBundle] pathForResource:@"file" ofType:@"zip"];
	
	//para arquivos com senha, pasta usar o método UnzipOpenFile:Password
	if ([zip  UnzipOpenFile:filePath]) {
		[zip UnzipFileTo:path overWrite:YES]; 
	}
	
	[zip UnzipCloseFile];
	[zip release];

}

@end