抽屉效果功能实现
一、.h文件
@interface
HMDrawViewController :
UIViewController
@property
(nonatomic,
weak,
readonly)
UIView *mainView;
@property
(nonatomic,
weak,
readonly)
UIView *leftView;
@property
(nonatomic,
weak,
readonly)
UIView *rightView;
@end
二、.m文件
@interface
HMDrawViewController
()
@property
(nonatomic,
assign)
BOOL isDraging;
@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：
抽屉效果的固定的高度是写死的，可以定义一个宏，方便后期的维护。
算法：
offsetY =
offsetX *
60
/
320
scale = currentH / screenH
currentH = screenH –
2 * offsetY
x = frame. origin.x + offsetX
h = frame.size.height * scale
w = frame.size.weight * scale
y =( screenH – h ) *
0.5
#define HMRTarget
250
#define HMLTarget -220
/*
_mainView.frame.origin.x > screenW * 0.5
定位到右边
CGRectGetMaxX(_mainView.frame) < screenW * 0.5
定位到左边
-220
*/
//
定位
- (void)touchesEnded:(NSSet
*)touches withEvent:(UIEvent
*)event
{
//
复位
if (_isDraging
==
NO &&
_mainView.frame.origin.x
!=
0) {
[UIView
animateWithDuration:0.25
animations:^{
_mainView.frame
=
self.view.bounds;
}];
}
CGFloat screenW = [UIScreen
mainScreen].bounds.size.width;
CGFloat target =
0;
if (_mainView.frame.origin.x
> screenW *
0.5) {
//
定位到右边
target =
HMRTarget;
}else
if (CGRectGetMaxX(_mainView.frame)
< screenW *
0.5) {
//
定位到左边
target =
HMLTarget;
}
[UIView
animateWithDuration:0.25
animations:^{
if (target) {
//
在需要定位左边或者右边
//
获取x轴偏移量
CGFloat offsetX = target -
_mainView.frame.origin.x;
//
设置当前主视图的frame
_mainView.frame
= [self
getCurrentFrameWithOffsetX:offsetX];
}else{
//
还原
_mainView.frame
=
self.view.bounds;
}
}];
_isDraging =
NO;
}
注意：
复位的时候，需要定义一个成员变量记录。
@end
注意：
知识点1：KVO观察者模式，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，当frame属性的值发生改变的时候就会调用下面这个方法。
- (void)observeValueForKeyPath:(NSString *)keyPath
ofObject:(id)object change:(NSDictionary *)change
context:(void *)context;
知识点2：抽屉效果的算法。