效果图

实现代码

- (void)setUpContraints
{CGFloat topImageCentery = (SCREEN_HEIGHT - 370 * PLUS_SCALE) / 2;[self.topIconView mas_makeConstraints:^(MASConstraintMaker *make) {make.centerX.mas_equalTo(0);make.centerY.equalTo(self.view.mas_top).with.offset(topImageCentery);}];[self.view layoutIfNeeded];
}- (void)topAnimation
{CASpringAnimation *springAnimation = [CASpringAnimation animationWithKeyPath:@"transform.scale"];springAnimation.mass = 1.5;springAnimation.stiffness = 400;springAnimation.damping = 20;springAnimation.initialVelocity = 0;springAnimation.duration = 1;springAnimation.fromValue = @0;springAnimation.toValue = @1;springAnimation.fillMode = kCAFillModeBoth;springAnimation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];[self.topIconView.layer addAnimation:springAnimation forKey:nil];
}