动画的抽屉效果

添加三个View

//
//  ViewController.m
//  UISenior17_抽屉效果
//
//  Created by lanou3g on 16/5/27.
//  Copyright © 2016年 张明杰. All rights reserved.
//

#import "ViewController.h"
//frame
#define XMGkeyPath(objc, keyPath) @(((void)objc.keyPath, #keyPath))
//获取屏幕的宽度
#define screenW [UIScreen mainScreen].bounds.size.width
//获取屏幕的高度
#define screenH [UIScreen mainScreen].bounds.size.height

#define targetR 300
#define targetL -200

#define XMGMaxY 100
@interface ViewController ()
@property (strong, nonatomic) IBOutlet UIView *mainV;

@property (weak, nonatomic) IBOutlet UIView *leftV;
@property (weak, nonatomic) IBOutlet UIView *ringhtV;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    [self setUpAllChildView];

    //添加拖拽手势
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];

    [_mainV addGestureRecognizer:pan];

    //KVO作用：时刻监听某个对象的某个属性的改变
    //_main frame属性的改变
    //Observer：观察者
    //KeyPath：监听的属性
    //NSKeyValueObservingOptionNew：表示监听新值得改变
    [_mainV addObserver:self forKeyPath:XMGkeyPath(_mainV, frame) options:(NSKeyValueObservingOptionNew) context:nil];

    //给控制器的view添加一个点按

    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tap)];
    [self.view addGestureRecognizer:tap];
}

- (void)setUpAllChildView{
    //left
    UIView *leftV = [[UIView alloc] initWithFrame:self.view.bounds];
      leftV.backgroundColor = [UIColor greenColor];
    [self.view addSubview:leftV];
    _leftV = leftV;

    // right
  UIView *rightV = [[UIView alloc] initWithFrame:self.view.bounds];
    rightV.backgroundColor = [UIColor blueColor];
         [self.view addSubview:rightV];
         _ringhtV = rightV;

         // main
         UIView *mainV = [[UIView alloc] initWithFrame:self.view.bounds];
         mainV.backgroundColor = [UIColor redColor];
         [self.view addSubview:mainV];
        _mainV = mainV;
}

//获取手势的偏移量

- (void)pan:(UIPanGestureRecognizer *)pan {

    //获取手势的偏移量
    CGPoint transP = [pan translationInView:_mainV];
    //获取x轴的偏移量，相对于上一次

    CGFloat offsetX = transP.x;
    //修改最新的main.frame
 _mainV.frame = [self frameWithOffsetX:offsetX];
    //复位
    [pan setTranslation:CGPointZero inView:_mainV];
    //判断下当前手指没有抬起，表示手势结束
    if (pan.state == UIGestureRecognizerStateEnded) {
        //手指抬起，定位// x>屏幕的一半，定位到右边某个位置
        CGFloat target = 0;
        if (_mainV.frame.origin.x > screenW*0.5) {
            target = targetR;
        } else if (CGRectGetMaxX(_mainV.frame) < screenW *0.5) {
            //最大的x<屏幕一半的时候，定义到左边某个位置
            target = targetL;

        }
        //获取x轴的偏移量
        CGFloat offsetX = target - _mainV.frame.origin.x;
        [UIView animateWithDuration:0.25 animations:^{
            _mainV.frame = [self frameWithOffsetX:offsetX];
        }];
    }

}
//给定一个x轴的偏移量计算下最先的main frame
- (CGRect)frameWithOffsetX:(CGFloat)offsetX {
    //获取当前main的frame

    CGRect frame = _mainV.frame;
    //计算当前的x.y.w.h
    //获取最新的x

    CGFloat x = frame.origin.x + offsetX;
    //获取最新的y
    CGFloat y = x /screenW *XMGMaxY;
    //当用户往左边移动的时候，_main.x < 0,y需要增加，为正
    if (frame.origin.x < 0) {
        y = -y;
    }

    //获取最新的h
    CGFloat h = screenH - 2 *y;
    //获取缩放比例

    CGFloat scale = h / screenH;
    //获取最新的w
    CGFloat w = screenW *scale;

    return CGRectMake(x, y, w, h);

}
//只要监听的属性一改变，就会调用
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary<NSString *,id> *)change context:(void *)context {
    if (_mainV.frame.origin.x > 0) {
        //往右滑动，显示左边控件，隐藏右边控件
        _ringhtV.hidden = YES;

    }else  if (_mainV.frame.origin.x < 0){
        _ringhtV.hidden = NO;
    }
}
- (void)dealloc {
    //移除观察者
    [_mainV removeObserver:self forKeyPath:XMGkeyPath(_mainV, frame)];

}

- (void)tap {
    if (_mainV.frame.origin.x != 0) {
        //把_mainV还原最开始的位置
        [UIView animateWithDuration:0.25 animations:^{
            _mainV.frame = self.view.bounds;
        }];
    }
}

@end

效果图如下：

　　正常的屏幕

往左滑动

往右滑动