iOS上拉拉出底部菜单，下拉菜单消失

产品经理让做一个仿饿了么底部菜单刚开始显示一部分，上拉时全部显示出来，向下滑时底部菜单再向下滑，只显示一部分，安卓有线程系统提供的，但是iOS系统没有，于是自己写了一个吧，供大家参考使用。
这是m文件内容，h文件内容就不写了，啥都没有

#import "HICDragView.h"
@interface HICDragView()
@property (nonatomic,strong)UIPanGestureRecognizer *pan;

@end
@implementation HICDragView
-(instancetype)init{
    
    if ([super init]) {
        [self setupPanGesture];
    }
    
    return self;
}
-(instancetype)initWithFrame:(CGRect)frame{
    
    if ([super initWithFrame:frame]) {
        [self setupPanGesture];
    }
    return self;
}
-(void)setupPanGesture{
     _pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panAction:)];
    _pan.minimumNumberOfTouches = 1;
    [self addGestureRecognizer:_pan];
    
}
- (void)panAction:(UIPanGestureRecognizer *)pan{

    CGPoint point = [pan translationInView:pan.view];
    
    if (pan.state == UIGestureRecognizerStateFailed || pan.state == UIGestureRecognizerStateEnded) {

        if (pan.view.top >= SCREEN_HEIGHT-395 && pan.view.top <= SCREEN_HEIGHT-395+130) {
           
            [UIView animateWithDuration:0.1 animations:^{
                pan.view.transform = CGAffineTransformIdentity;
                [pan setTranslation:CGPointZero inView:pan.view];
            }];
            
        }
        
        if (pan.view.top > SCREEN_HEIGHT-395+130 && pan.view.top <=SCREEN_HEIGHT-395+260) {
            [UIView animateWithDuration:0.1 animations:^{
                pan.view.transform = CGAffineTransformMakeTranslation(0, 260);
                [pan setTranslation:CGPointZero inView:pan.view];

            }];

        }


    }
    
    if ((pan.view.top >= SCREEN_HEIGHT-395 && pan.view.top <= SCREEN_HEIGHT-395+260)  && point.y>0) {
        pan.view.transform =CGAffineTransformTranslate(pan.view.transform,0, point.y);
              [pan setTranslation:CGPointZero inView:pan.view];
        
        if (pan.view.top >= SCREEN_HEIGHT-395+260) {
            pan.view.transform =CGAffineTransformTranslate(pan.view.transform,0, -point.y);
                  [pan setTranslation:CGPointZero inView:pan.view];

        }

    }
    if ((pan.view.top <= SCREEN_HEIGHT-395+260 && pan.view.top > SCREEN_HEIGHT-395) && point.y <0) {
        pan.view.transform =CGAffineTransformTranslate(pan.view.transform,0, point.y);
        [pan setTranslation:CGPointZero inView:pan.view];
        if (pan.view.top <= SCREEN_HEIGHT-395) {
             pan.view.transform =CGAffineTransformTranslate(pan.view.transform,0, -point.y);
            [pan setTranslation:CGPointZero inView:pan.view];
        }
    }
    
    

    
//    pan.view.transform =CGAffineTransformMakeTranslation(point.x, point.y);

}
@end

外面使用时：

HICDragView * view = [[HICDragView alloc] init];
    view.backgroundColor = [UIColor yellowColor];
    [self.view addSubview:view];
    [view mas_makeConstraints:^(MASConstraintMaker *make) {
        make.left.right.equalTo(self.view);
        make.bottom.equalTo(self.view);
        make.height.mas_equalTo(395);
    }];
    view.transform = CGAffineTransformMakeTranslation(0, 260);//默认向下偏移了个260