self.nav = [[[NavViewController alloc] initWithRootViewController:self.viewController] autorelease];
[self.nav.navigationBar setBackgroundImage:[UIImage imageNamed:@"navbg"] forBarMetrics:UIBarMetricsDefault];
NSDictionary *dict = [NSDictionary dictionaryWithObjectsAndKeys:[UIColor whiteColor],UITextAttributeTextColor,[UIColor blackColor],UITextAttributeTextShadowColor,[UIFont boldSystemFontOfSize:20.0],UITextAttributeFont,CGSizeMake(0, -1.0),UITextAttributeTextShadowOffset, nil];
self.nav.navigationBar.titleTextAttributes = dict;
有些属性名称在iOS8上又新的替代，只用将key名称替代即可
