通过kvc修改导航条颜色

UIView *navBgView = [[UIImageView alloc] initWithFrame:CGRectMake(0, -20, SCREENWIDTH, 64)];

navBgView.backgroundColor = ZCCRGBColor(72, 170, 255, 1.0);

[self.navigationController.navigationBar setValue:navBgView forKey:@"backgroundView"];