学步园

@property
(nonatomic,

weak,
readonly)

UIView *mainView;
@property
(nonatomic,

weak,
readonly)

UIView *leftView;
@property
(nonatomic,

weak,
readonly)

UIView *rightView;

@end

@implementation
HMDrawViewController

- (void)viewDidLoad
{
   
// UIViewController
    [super
viewDidLoad];
   
// Do any additional setup after loading the view.
  
   
// 1.添加子控件
    [self
addChildView];
#warning
第三步
观察_mainView的frame改变
   
// 2.监听
   
/**
     * 
给_mainView添加一个观察者
     *
     *  KeyPath：监听frame这个属性
     *
     *  options：监听新值的改变
     */
    [_mainView
addObserver:self
forKeyPath:@"frame"
options:NSKeyValueObservingOptionNew
context:nil];
  
}

//
当_mainView的frame属性改变的时候就会调用
- (void)observeValueForKeyPath:(NSString
*)keyPath ofObject:(id)object change:(NSDictionary
*)change context:(void
*)context
{
   
NSLog(@"%@",
NSStringFromCGRect(_mainView.frame));
   
   
if (_mainView.frame.origin.x
<
0) {
//
往左移动
       
//
显示右边
       
_rightView.hidden
=
NO;
       
//
隐藏左边
       
_leftView.hidden
=
YES;
    }else

if (_mainView.frame.origin.x
>
0){
//
往右移动
       
//
显示左边
       
_rightView.hidden
=
YES;
       
//
隐藏右边
       
_leftView.hidden
=
NO;
       
    }
}

#warning
第一步
- (void)addChildView
{
   
// left
   
UIView *leftView = [[UIView
alloc]
initWithFrame:self.view.bounds];
    leftView.backgroundColor
= [UIColor
greenColor];
    [self.view
addSubview:leftView];
   
_leftView = leftView;
   
   
// right
   
UIView *rightView = [[UIView
alloc]
initWithFrame:self.view.bounds];
    rightView.backgroundColor
= [UIColor
blueColor];
    [self.view
addSubview:rightView];
   
_rightView = rightView;
   
   
// mainView
   
UIView *mainView = [[UIView
alloc]
initWithFrame:self.view.bounds];
    mainView.backgroundColor
= [UIColor
redColor];
    [self.view
addSubview:mainView];
   
_mainView = mainView;
}

#warning
第二步
- (void)touchesMoved:(NSSet
*)touches withEvent:(UIEvent
*)event
{
   
//
获取UITouch对象
   
UITouch *touch = [touches
anyObject];
   
   
//
获取当前点
   
CGPoint currentPoint = [touch
locationInView:self.view];
   
   
//
获取上一个点
   
CGPoint prePoint = [touch
previousLocationInView:self.view];
   
   
// x轴偏移量：当手指移动一点的时候，x偏移多少
   
CGFloat offsetX = currentPoint.x
- prePoint.x;
   
   
//
设置当前主视图的frame
   
_mainView.frame
= [self
getCurrentFrameWithOffsetX:offsetX];
   
   
   
_isDraging =

YES;
}
#warning
第四步
#define HMMaxY
60
//
当手指偏移一点，根据X轴的偏移量算出当前主视图的frame
- (CGRect)getCurrentFrameWithOffsetX:(CGFloat)offsetX
{
   
CGFloat screenW = [UIScreen
mainScreen].bounds.size.width;
   
CGFloat screenH = [UIScreen
mainScreen].bounds.size.height;
   
   
//
获取y轴偏移量，手指每移动一点，y轴偏移多少
   
CGFloat offsetY = offsetX *
HMMaxY
/ screenW;
   
   
CGFloat scale = (screenH -
2
* offsetY) / screenH;
   
   
if (_mainView.frame.origin.x
<
0) {
//
往左边滑动
        scale = (screenH +
2 * offsetY) / screenH;
    }
   
   
//
获取之前的frame
   
CGRect frame =

_mainView.frame;
    frame.origin.x
+= offsetX;
    frame.size.height
= frame.size.height
*scale;
    frame.size.width
= frame.size.width
*scale;
    frame.origin.y
= (screenH - frame.size.height)
*
0.5;
   
   
return frame;
}

注意：

x = frame. origin.x + offsetX
h = frame.size.height * scale
w = frame.size.weight * scale
y =( screenH – h ) *
0.5