iOS如何用100行代码实现简单的抽屉效果

#import <UIKit/UIKit.h>

@interface MainViewController : UIViewController
+ (instancetype)mainViewControllerWithLeftViewController:(UIViewController *)leftViewController withMainPageViewController:(UIViewController *)mainPageViewController;
@end

#import "MainViewController.h"

#define KWidth self.view.frame.size.width
#define KHeight self.view.frame.size.height

@interface MainViewController ()
@property (nonatomic,strong)UIViewController *leftVC;
@property (nonatomic,strong)UIViewController *centerVC;
@property (nonatomic,assign)BOOL isSlider;
@property (nonatomic,strong)UIView *corverView;
@end


@implementation MainViewController
+ (instancetype)mainViewControllerWithLeftViewController:(UIViewController *)leftViewController withMainPageViewController:(UIViewController *)mainPageViewController{

  MainViewController *mainVC = [[MainViewController alloc] init];
  mainVC.leftVC = leftViewController;
  mainVC.centerVC = mainPageViewController;
  return mainVC;
}
- (void)viewDidLoad{
  [super viewDidLoad];
  self.isSlider = NO;
  self.view.backgroundColor = [UIColor whiteColor];
  [self addChildViewController:self.leftVC];
  [self.view addSubview:self.leftVC.view];
  [self addChildViewController:self.centerVC];
  [self.view addSubview:self.centerVC.view];
  // 给左视图和主视图添加手势
  [self addGestureForView];
}
// 给主视图添加遮盖
- (void)addCorverView{
  if (self.corverView) {
    [self.corverView removeFromSuperview];
    self.corverView = nil;
  }
  self.corverView = [[UIView alloc] initWithFrame:self.centerVC.view.bounds];
  _corverView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.0];
  [self.centerVC.view addSubview:self.corverView];
}
// 移除主视图遮盖
- (void)removeCoverView{
  if (self.corverView) {
    [self.corverView removeFromSuperview];
    self.corverView = nil;
  }
}
// 给左视图和主视图添加手势
- (void)addGestureForView{
  UISwipeGestureRecognizer *rightGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeRightAction:)];
  rightGesture.direction = UISwipeGestureRecognizerDirectionRight;
  [self.centerVC.view addGestureRecognizer:rightGesture];
  UISwipeGestureRecognizer *leftGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeLeftAction:)];
  leftGesture.direction = UISwipeGestureRecognizerDirectionLeft;
  [self.centerVC.view addGestureRecognizer:leftGesture];
  UISwipeGestureRecognizer *leftVCLeftSwipeGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(leftVCLeftSwipeAction:)];
  leftVCLeftSwipeGesture.direction = UISwipeGestureRecognizerDirectionLeft;
  [self.leftVC.view addGestureRecognizer:leftVCLeftSwipeGesture];
}
- (void)swipeRightAction:(id)sender{
  [self moveView:self.centerVC.view scale:0.8 panValue:KWidth];
  self.isSlider = YES;
  [self addCorverView];
}
- (void)swipeLeftAction:(id)sender{
  [self moveView:self.centerVC.view scale:1 panValue:KWidth / 2];
  self.isSlider = NO;
  [self removeCoverView];
}
- (void)leftVCLeftSwipeAction:(id)sender{
  [self moveView:self.centerVC.view scale:1 panValue:KWidth / 2];
  self.isSlider = NO;
  [self removeCoverView];
}
// 平移和缩放一个视图
- (void)moveView:(UIView *)view scale:(CGFloat)scale panValue:(CGFloat)value{
  [UIView beginAnimations:nil context:nil];
  view.transform = CGAffineTransformScale(CGAffineTransformIdentity,scale,scale);
  view.center = CGPointMake(value, view.center.y);
  [UIView commitAnimations];
}
@end