一、簡介

       有時候我們在做程序的時候,項目要求我們給用戶提示信息的時候,從頂部自動下拉下來,前些日子我接到過這樣的需求,感覺用第三方的集成進來,如果以后修改樣式的話或者其它的需求會很麻煩,所以我自己寫了一個,代碼有點簡單,請大家指導一下,有什么意見或者有什么疑問可以直接評論詢問我,很樂意和大家一起探討學習.

二、代碼

1.創建一個單例,我是繼承NSOject的

+(instancetype)shareInstance{    static ShowChatStateView *stateView = nil;    static dispatch_once_t onceToken;    dispatch_once(&onceToken, ^{        stateView = [[ShowChatStateView alloc]init];    });    return stateView;}

2.初始化UIWindow

-(instancetype)init{    self = [super init];    id <UIapplicationDelegate> delegate = [[UIApplication sharedApplication] delegate];    if ([delegate respondsToSelector:@selector(window)])    {        self.window = [delegate performSelector:@selector(window)];    }    else    {        self.window = [[UIApplication sharedApplication] keyWindow];    }    [self createUI];    return self;    }3.創建UILabel,使label唯一

-(void)createUI{    if (self.label == nil)    {        self.label = [[UILabel alloc]initWithFrame:CGRectMake(0, -64, SCREEN_WIDTH, 64)];        self.label.textAlignment = NSTextAlignmentCenter;        self.label.textColor = [UIColor whiteColor];        self.label.backgroundColor = [MyTool colorWithString:@"50D2C2"];        self.label.font = [UIFont systemFontOfSize:Font(14.0f)];        self.label.alpha = 0.f;    }    if (self.label.superview == nil)    {        [self.window addSubview:self.label];    }}4.將文字顯示在Label上,并且從上面自動下拉,隔段時間(自己設定)在彈回去

-(void)show{    if (!self.label.alpha)    {        self.label.alpha = 1.f;        CGRect rect = self.label.frame;        rect.origin.y = 0;        [UIView animateWithDuration:0.5 animations:^{            self.label.frame = rect;        } completion:^(BOOL finished) {            CGRect rect = self.label.frame;            rect.origin.y = -64;            [UIView animateWithDuration:0.5 delay:1.0 options:UIViewAnimationOptionCurveEaseIn animations:^{                self.label.frame = rect;            } completion:^(BOOL finished) {                self.label.alpha = 0.f;            }];        }];    }}-(void)showLabelWithString:(NSString *)string{    self.label.text = string;    [self show];}5.調用方法

[[ShowChatStateView shareInstance] showLabelWithString:@"您已簽過到"];

三、總結

我是利用UIWindow來實現下拉,這樣有導航欄也不影響view的向下彈出,如果你有更好的方法,歡迎討論,下面是效果圖: