Can we open pdf file using UIWebView on iOS?

Yes, this can be done with the UIWebView.

If you are trying to display a PDF file residing on a server somewhere, you can simply load it in your web view directly:

Objective-C

UIWebView *webView = [[UIWebView alloc] initWithFrame:CGRectMake(10, 10, 200, 200)];

NSURL *targetURL = [NSURL URLWithString:@"https://www.example.com/document.pdf"];
NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];
[webView loadRequest:request];

[self.view addSubview:webView];

Swift

let webView = UIWebView(frame: CGRect(x: 10, y: 10, width: 200, height: 200))

let targetURL = NSURL(string: "https://www.example.com/document.pdf")! // This value is force-unwrapped for the sake of a compact example, do not do this in your code
let request = NSURLRequest(URL: targetURL)
webView.loadRequest(request)

view.addSubview(webView)

Or if you have a PDF file bundled with your application (in this example named "document.pdf"):

Objective-C

UIWebView *webView = [[UIWebView alloc] initWithFrame:CGRectMake(10, 10, 200, 200)];

NSURL *targetURL = [[NSBundle mainBundle] URLForResource:@"document" withExtension:@"pdf"];
NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];
[webView loadRequest:request];

[self.view addSubview:webView];

Swift

let webView = UIWebView(frame: CGRect(x: 10, y: 10, width: 200, height: 200))

let targetURL = NSBundle.mainBundle().URLForResource("document", withExtension: "pdf")! // This value is force-unwrapped for the sake of a compact example, do not do this in your code
let request = NSURLRequest(URL: targetURL)
webView.loadRequest(request)

view.addSubview(webView)

You can find more information here: Technical QA1630: Using UIWebView to display select document types.

UIWebviews can also load the .pdf using loadData method, if you acquire it as NSData:

[self.webView loadData:self.pdfData 
              MIMEType:@"application/pdf" 
      textEncodingName:@"UTF-8" 
               baseURL:nil];

use this for open pdf file in webview

NSString *path = [[NSBundle mainBundle] pathForResource:@"mypdf" ofType:@"pdf"];
NSURL *targetURL = [NSURL fileURLWithPath:path];
NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];
UIWebView *webView=[[UIWebView alloc] initWithFrame:CGRectMake(0, 0, 300, 300)];
[[webView scrollView] setContentOffset:CGPointMake(0,500) animated:YES];
[webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"window.scrollTo(0.0, 50.0)"]];
[webView loadRequest:request];
[self.view addSubview:webView];
[webView release];

NSString *folderName=[NSString stringWithFormat:@"/documents/%@",[tempDictLitrature objectForKey:@"folder"]];
NSString *fileName=[tempDictLitrature objectForKey:@"name"];
[self.navigationItem setTitle:fileName];
NSString *type=[tempDictLitrature objectForKey:@"type"];

NSString *path=[[NSBundle mainBundle]pathForResource:fileName ofType:type inDirectory:folderName];

NSURL *targetURL = [NSURL fileURLWithPath:path];
NSURLRequest *request = [NSURLRequest requestWithURL:targetURL];
webView=[[UIWebView alloc] initWithFrame:CGRectMake(0, 0, 1024, 730)];
[webView setBackgroundColor:[UIColor lightGrayColor]];
webView.scalesPageToFit = YES;

[[webView scrollView] setContentOffset:CGPointZero animated:YES];
[webView stringByEvaluatingJavaScriptFromString:[NSString stringWithFormat:@"window.scrollTo(0.0, 50.0)"]];
[webView loadRequest:request];
[self.view addSubview:webView];

Swift version:

if let docPath = NSBundle.mainBundle().pathForResource("sample", ofType: "pdf") {
    let docURL = NSURL(fileURLWithPath: docPath)
    webView.loadRequest(NSURLRequest(URL: docURL))
}