在navigation下方添加视图动画

这里我已经将这个动画封装成一个类方法，其中颜色，字体大小，背景图片之类的皆可自定义。此处的动画是建立在有navigation下方出现，在继而消失在navigation下方，假如想有什么多的功能，比如点击弹出View跳出一个控制器等等，效果图如下所示

//.h文件
#import <Foundation/Foundation.h>
@interface YLAnimationShow : NSObject
+ (void)showString:(NSString *)string navigationController:(UINavigationController *)navigationController;
@end
//.m文件
#import "YLAnimationShow.h"
@implementation YLAnimationShow
+ (void)showString:(NSString *)string navigationController:(UINavigationController *)navigationController
{
    UILabel *countLabel = [[UILabel alloc] init];
    countLabel.backgroundColor = [UIColor purpleColor];
    countLabel.width = WindowWidth;
    countLabel.height = 35;    
    countLabel.text = string;  
    countLabel.textAlignment = NSTextAlignmentCenter;
    countLabel.textColor = [UIColor whiteColor];
    countLabel.font = [UIFont systemFontOfSize:16]; 
    // 3.添加
    countLabel.y = 64 - countLabel.height;
    // 将label添加到导航控制器的view中，并且是盖在导航栏下边
    [navigationController.view insertSubview:countLabel belowSubview:navigationController.navigationBar];
    CGFloat duration = 1.0; // 动画的时间
    [UIView animateWithDuration:duration animations:^{
        countLabel.transform = CGAffineTransformMakeTranslation(0, countLabel.height);
    } completion:^(BOOL finished) {
        // 延迟1s后，再利用1s的时间，让label往上移动一段距离（回到一开始的状态）
        CGFloat delay = 1.0; // 延迟1s
        // UIViewAnimationOptionCurveLinear:匀速
        [UIView animateWithDuration:duration delay:delay options:UIViewAnimationOptionCurveLinear animations:^{
            countLabel.transform = CGAffineTransformIdentity;
        } completion:^(BOOL finished) {
            [countLabel removeFromSuperview];
        }];
    }];
}
@end

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