import "RGWebView.h"

@interface RGWebView()

@property (nonatomic, strong) UIView *redView;
@property (nonatomic, strong) UIView *blueView;
@property (assign, nonatomic) NSInteger start;
@property (assign, nonatomic) BOOL backBool;
@property (assign, nonatomic) BOOL forwardBool;

@end

@implementation RGWebView

-(instancetype)initWithFrame:(CGRect)frame{
if (self = [super initWithFrame:frame]) {
self.start = 0;
self.backBool = NO;
self.forwardBool = NO;
[self setupUI];
}
return self;
}

-(void)setupUI{
if (nil == _redView) {
_redView = [[UIView alloc]init];
_redView.backgroundColor = [UIColor redColor];
[self addSubview:_redView];
}
if (nil == _blueView) {
_blueView = [[UIView alloc]init];
_blueView.backgroundColor = [UIColor blueColor];
[self addSubview:_blueView];
}
UIPanGestureRecognizer *gesture = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(panGesture:)];
[self addGestureRecognizer:gesture];
}
-(void)layoutSubviews{
[super layoutSubviews];
self.redView.frame = CGRectMake(-100, 100, 100, 50);
self.blueView.frame = CGRectMake(KScreen_Width, 100, 100, 50);
}

pragma mark === gesture===

• (void)panGesture:(UIPanGestureRecognizer *)sender{
  if (![self canGoBack] && ![self canGoForward]) {
  return;
  }

  //状态
  if (sender.state == UIGestureRecognizerStateBegan) {

    CGPoint location = [sender locationInView:self];
    self.start = location.x;
  

  }else if (sender.state == UIGestureRecognizerStateChanged) {

    CGPoint location = [sender locationInView:self];
    if (location.x - self.start > 0 && [self canGoBack]) {
     
        self.redView.x = MIN(location.x - self.start, 100) - 100;
        self.backBool = YES;
        
    }else{
        if ([self canGoForward]) {
            self.blueView.x = KScreen_Width - MIN(-(location.x - self.start), 100);
            self.forwardBool = YES;
        }
    }
  

  }else if (sender.state == UIGestureRecognizerStateEnded) {
  self.redView.x = -100;
  self.blueView.x = KScreen_Width;
  self.start = 0;
  if (self.backBool) {
  [self goBack];
  }else if (self.forwardBool) {
  [self goForward];
  }
  self.backBool = NO;
  self.forwardBool = NO;
  }
  }

@end