//Try like this
NSString *urlstr=@"www.example.com/yy.pdf";
web=nil;
web=[[UIWebView alloc] initWithFrame:CGRectMake(0, 98, 320, 367)];
web.delegate=self;
[self.view addSubview:web];
[web loadRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:urlstr]]];
UIPinchGestureRecognizer *pgr = [[UIPinchGestureRecognizer alloc]
initWithTarget:self action:@selector(handlePinch:)];
pgr.delegate = self;
[web addGestureRecognizer:pgr];
// Target Action
- (IBAction)handlePinch:(UIPinchGestureRecognizer *)recognizer
{
recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);
recognizer.scale = 1;
}
Before this add UIGestureRecognizerDelegate in .h. Hope it will helps you..