The behavior of tintColor for bars has changed in iOS 7.0. It no longer affects the bar's background.
From the documentation:
barTintColor Class Reference
The tint color to apply to the navigation bar background.
@property(nonatomic, retain) UIColor *barTintColor
Discussion
This color is made translucent by default unless you set the translucent property to NO.
Availability
Available in iOS 7.0 and later.
Declared In
UINavigationBar.h
Code
NSArray *ver = [[UIDevice currentDevice].systemVersion componentsSeparatedByString:@"."];
if ([[ver objectAtIndex:0] intValue] >= 7) {
    // iOS 7.0 or later   
    self.navigationController.navigationBar.barTintColor = [UIColor redColor];
    self.navigationController.navigationBar.translucent = NO;
}else {
    // iOS 6.1 or earlier
    self.navigationController.navigationBar.tintColor = [UIColor redColor];
}
We can also use this to check iOS Version as mention in  iOS 7 UI Transition Guide
if (floor(NSFoundationVersionNumber) <= NSFoundationVersionNumber_iOS_6_1) {
        // iOS 6.1 or earlier
        self.navigationController.navigationBar.tintColor = [UIColor redColor];
    } else {
        // iOS 7.0 or later     
        self.navigationController.navigationBar.barTintColor = [UIColor redColor];
        self.navigationController.navigationBar.translucent = NO;
    }
EDIT
Using xib
