在我們app開發(fā)中珠十，經(jīng)常要用到加載動畫疼邀，寫了個(gè)加載動畫誓焦，封裝在AXLoadingAnimationView類中，主要的代碼如下诺祸。
UI初始化代碼

-(void)setupUI
{
    UIView *leftView = [[UIView alloc] init];
    leftView.backgroundColor = [UIColor redColor];
    self.leftBallView = leftView;
    [self addSubview:leftView];
    
    UIView *middleView = [[UIView alloc]init];
    middleView.backgroundColor = [UIColor blackColor];
    self.middleBallView = middleView;
    [self addSubview:middleView];
    
    UIView *rightView = [[UIView alloc]init];
    rightView.backgroundColor = [UIColor blueColor];
    self.rightBallView = rightView;
    [self addSubview:rightView];
    
    self.middleBallView.frame = CGRectMake(0, 0, self.ballSize, self.ballSize);
    self.leftBallView.frame = CGRectMake(0, 0, self.ballSize, self.ballSize);
    self.rightBallView.frame = CGRectMake(0, 0, self.ballSize, self.ballSize);
    
    self.middleBallView.center = CGPointMake(self.bounds.size.width/2, self.bounds.size.height/2);//self.center;
    self.leftBallView.center = CGPointMake(self.middleBallView.center.x - self.ballSize*2, self.middleBallView.center.y);
    self.rightBallView.center = CGPointMake(self.middleBallView.center.x + self.ballSize*2, self.middleBallView.center.y);
    
    [self setCornerWithView:self.leftBallView borderColor:[UIColor clearColor] borderWidth:1 cornerRadius:self.ballSize/2];
     [self setCornerWithView:self.middleBallView borderColor:[UIColor clearColor] borderWidth:1 cornerRadius:self.ballSize/2];
     [self setCornerWithView:self.rightBallView borderColor:[UIColor clearColor] borderWidth:1 cornerRadius:self.ballSize/2];
}

當(dāng)我們的視圖添加到父視圖或者從父視圖移除會調(diào)用如下函數(shù),可以看到當(dāng)添加到父視圖時(shí)開始動畫吴叶，當(dāng)從父視圖移除時(shí)，停止動畫序臂。

-(void)didMoveToSuperview
{
    if (self.superview) {
        [self startAnimation];
    }
    else
    {
        [self stopAnimation];
    }
}

開始動畫

-(void)startAnimation
{
    self.readyStop = NO;
    self.isAnimation = YES;
    [self performAnimation];
}

執(zhí)行動畫performAnimation函數(shù)代碼如下：

-(void)performAnimation
{
    [UIView animateWithDuration:0.3 animations:^{
        
        self.leftBallView.centerX = self.leftBallView.centerX + self.ballSize*2;
        self.rightBallView.centerX = self.rightBallView.centerX - self.ballSize*2;
        self.leftBallView.alpha = 0.5;
        self.rightBallView.alpha = 0.5;
        
    } completion:^(BOOL finished) {
        UIColor *cr = self.leftBallView.backgroundColor;
        self.leftBallView.backgroundColor = self.middleBallView.backgroundColor;
        self.middleBallView.backgroundColor = cr;
        [UIView animateWithDuration:0.3 animations:^{
            self.leftBallView.alpha = 0.5;
            self.rightBallView.alpha = 0.5;
            
            self.leftBallView.centerX = self.leftBallView.centerX + self.ballSize*2;
            self.rightBallView.centerX = self.rightBallView.centerX - self.ballSize*2;
            
        } completion:^(BOOL finished) {
            UIView *vw = self.leftBallView;
            self.leftBallView = self.rightBallView;
            self.rightBallView = vw;
            
            if (!self.readyStop) {
                [self performAnimation];
            }
        }];
    }];
}

具體代碼上傳到github：https://github.com/jiangtaidi/LoadingAnimationView.git