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。
