NSURL initialization from NSString

NSURL initialization from NSString

I am tring to display web view in ipad by creating a NSURL from NSString.
Code is following...
NSLog(@"string s= %@",s); // s display url string
NSURL *url = [[NSURL alloc] initWithString:s];
NSLog(@"%@, str= %@",url, s);// but url null
NSURLRequest *requestObj = [[NSURLRequest alloc ] initWithURL:url];
NSLog(@"%@",requestObj);
[self.webView loadRequest:requestObj];