第一步、在需要導航欄透明的頁面進行設置

//允許半透明狀態

[self.navigationController.navigationBar setTranslucent:YES];

//畫一張寬為屏幕寬，高為64的透明圖片

UIColor *color = [UIColor clearColor];

CGRect rect = CGRectMake(0.0f, 0.0f, [UIScreen mainScreen].bounds.size.width, 64);

UIGraphicsBeginImageContext(rect.size);

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetFillColorWithColor(context, [color CGColor]);

CGContextFillRect(context, rect);

UIImage *img = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

//將透明圖片設為導航欄的背景圖片

[self.navigationController.navigationBar setBackgroundImage:img forBarMetrics:UIBarMetricsDefault];

[self.navigationController.navigationBar setBackgroundColor:[UIColor clearColor]];

//對超出父視圖的子視圖不進行裁剪

self.navigationController.navigationBar.clipsToBounds = YES;

第二步、將導航欄改為不透明

[self.navigationController.navigationBar setTranslucent:NO];

CGRect rect = CGRectMake(0.0f, 0.0f, [UIScreen mainScreen].bounds.size.width, 64);

UIGraphicsBeginImageContext(rect.size);

CGContextRef context = UIGraphicsGetCurrentContext();

CGContextSetFillColorWithColor(context, [ColorRGB(41.0, 41.0, 41.0, 1) CGColor]);

CGContextFillRect(context, rect);

UIImage *img = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

[self.navigationController.navigationBar setBackgroundImage:img forBarMetrics:UIBarMetricsDefault];

self.navigationController.navigationBar.clipsToBounds = NO;