iOS 顶部通知动态Label

#import 

@interface MWDynamicLabel : UIView

@property(nonatomic, copy) NSString* text;
@property(nonatomic, strong) UIColor* textColor;
@property(nonatomic, strong) UIFont* font;
@property(nonatomic, assign) CGFloat speed;
@property(nonatomic, strong) UILabel* contentLabel;

@end

#import "MWDynamicLabel.h"

@interface MWDynamicLabel()

@property(nonatomic, assign) BOOL animationBreak;

@end

@implementation MWDynamicLabel

- (UILabel *)contentLabel
{
    if (!_contentLabel) {
        UILabel* contentLabel = [[UILabel alloc] init];
        [contentLabel sizeToFit];
        contentLabel.backgroundColor = [UIColor clearColor];
        contentLabel.textAlignment = NSTextAlignmentCenter;
        _contentLabel = contentLabel;
    }
    return _contentLabel;
}


- (instancetype)initWithFrame:(CGRect)frame
{
    if (self = [super initWithFrame:frame]) {
        
        [self setup];
    }
    return self;
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
    if (self = [super initWithCoder:aDecoder])
    {
        [self setup];
    }
    return self;
}


- (void)setup
{
    [self addSubview:self.contentLabel];
    
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(layoutSubviews) name:UIApplicationWillEnterForegroundNotification object:[UIApplication sharedApplication]];
}

- (void)setFrame:(CGRect)frame
{
    [super setFrame:frame];
    
    CAShapeLayer* maskLayer = [CAShapeLayer layer];
    maskLayer.path = [UIBezierPath bezierPathWithRect:self.bounds].CGPath;
    self.layer.mask = maskLayer;
}

- (void)setText:(NSString *)text
{
    self.contentLabel.text = text;
    
    [self.contentLabel sizeToFit];
    
}

- (void)setFont:(UIFont *)font
{
    self.contentLabel.font = font;
    [self.contentLabel sizeToFit];
    
    CGRect frame = self.frame;
    if (frame.size.height < font.lineHeight) {
        frame.size.height = font.lineHeight;
        self.frame = frame;
    }
    
}

- (void)setTextColor:(UIColor *)textColor
{
    self.contentLabel.textColor = textColor;
}

- (void)willMoveToWindow:(UIWindow *)newWindow
{
    [super willMoveToWindow:newWindow];
    if (newWindow)
    {
        [self addAnimation];
    }
}


- (void)layoutSubviews
{
    [super layoutSubviews];
    if (self.animationBreak) {
        [self addAnimation];
    }
}


- (void)addAnimation
{
    if (self.frame.size.width >= self.contentLabel.frame.size.width) {
        
        CGRect rectFrame = self.contentLabel.frame;
        rectFrame.origin.x = (self.frame.size.width-self.contentLabel.frame.size.width)/2;
        self.contentLabel.frame = rectFrame;
        return;
        
    }
    
    [self.contentLabel.layer removeAllAnimations];
    
    CGFloat space = self.contentLabel.frame.size.width - self.frame.size.width;
    
    CAKeyframeAnimation* keyFrame = [CAKeyframeAnimation animation];
    keyFrame.keyPath = @"transform.translation.x";
    keyFrame.values = @[@(0), @(-space), @(0)];
    keyFrame.repeatCount = NSIntegerMax;
    keyFrame.duration = self.speed * self.contentLabel.text.length;
    keyFrame.timingFunctions = @[[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut],
                                 [CAMediaTimingFunction functionWithControlPoints:0 :0 :0.5 :0.5]];
    __weak typeof(self) weakSelf = self;
    keyFrame.delegate = weakSelf;
    
    [self.contentLabel.layer addAnimation:keyFrame forKey:nil];
}

- (void)animationDidStop:(CAAnimation *)anim finished:(BOOL)flag
{
    self.animationBreak = !flag;
}


- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
}

@end