转：iOS界面-抽屉式交互

转自：

http://blog.sina.com.cn/s/blog_63fa2cac01018n97.html

1、介绍

用过网易新闻客户端的同学都会发现，网易新闻向左滑动时，左侧的导航栏会跟着拖动出来，新闻内容列表会拉到最右侧。像一个抽屉拉出来一样。很酷。除了网易新闻，现在好多应用都采用了这样的交互。

这个交互效果主要用到两个手势，一个是pan拖拽，一个是tap点击。拖拽可以把抽屉拉出来，再推回去。点击可以把抽屉推回去。

效果如下：

那么这个效果如何实现呢？

2、实现思路和步骤

思路：从实现的效果分析出来，可以这样实现：

这个交互是由两个View组成，左侧导航的View在下面，显示内容列表的View在上面，内容列表的View覆盖住了导航View,拖动内容列表的View向右，这时候导航View就显示出来了。

实现步骤：

1. 自定义一个View，它做为显示内容的View。给这个View添加两个手势，pan拖拽，tap点击。
2. 当拖拽这个View时，让view.center向右移动，这样就能看到内容View向右移动了。
3. 定义一个抽屉打开停止时的x值为：OPENCENTERX，这个是内容View最终停止的位置
4. 当内容View越过中间靠右的一个x值时，view自动向右动画移动到右边位置停下。
5. 当内容View在打开的状态下，点击内容View，利用UIView动画把内容View.center移动回到中间。
6. 设置内容View的阴影效果

3、代码实现

新建CustomView继承UIView

#import

@interface CustomView : UIView
{
    CGPoint openPointCenter;
    CGPoint closePointCenter;
}
-(id)initWithView:(UIView*)contentview parentView:(UIView*) parentview;

@property (nonatomic, strong) UIView *parentView; //抽屉视图的父视图
@property (nonatomic, strong) UIView *contenView; //抽屉显示内容的视图
@end

两个手势在Custom里实现，并在初始化的时候传入内容View和父视图。

#import "CustomView.h"

#define OPENCENTERX 220.0
#define DIVIDWIDTH 70.0 //OPENCENTERX 对应确认是否打开或关闭的分界线。

@implementation CustomView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code
    }
    return self;
}

- (id)initWithView:(UIView *)contentview parentView:(UIView *)parentview
{
    self = [super initWithFrame:CGRectMake(0,0,contentview.frame.size.width, contentview.frame.size.height)];
    if (self) {
        self.contenView = contentview;
        self.parentView = parentview;
       
        [self addSubview:contentview];
        UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc]
                                                        initWithTarget:self
                                                        action:@selector(handlePan:)];
        [self addGestureRecognizer:panGestureRecognizer];
       
        UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc]
                                                        initWithTarget:self
                                                        action:@selector(handleTap:)];

        [self addGestureRecognizer:tapGestureRecognizer];
        openPointCenter = CGPointMake(self.parentView.center.x + OPENCENTERX,
                                     self.parentView.center.y);
       
        NSLog(@"openPointCenter x:%f, openPointCenter y:%f",
              openPointCenter.x,
              openPointCenter.y);
    }
    return self;
}

-(void) handlePan:(UIPanGestureRecognizer*) recognizer
{
    CGPoint translation = [recognizer translationInView:self.parentView];
   
    float x = self.center.x + translation.x;
    NSLog(@"translation x:%f", translation.x);
 
    if (x < self.parentView.center.x) {
        x = self.parentView.center.x;
    }
    self.center = CGPointMake(x, openPointCenter.y);
   
    if(recognizer.state == UIGestureRecognizerStateEnded)
    {
            [UIView animateWithDuration:0.75
                                  delay:0.01
                                options:UIViewAnimationCurveEaseInOut
                             animations:^(void)
            {
                if (x > openPointCenter.x -  DIVIDWIDTH) {
                    self.center = openPointCenter;
                }else{
                    self.center = CGPointMake(openPointCenter.x - OPENCENTERX,
                                             openPointCenter.y); 
                }
            }completion:^(BOOL isFinish){ 
            }];
        }
    [recognizer setTranslation:CGPointZero inView:self.parentView];
}

-(void) handleTap:(UITapGestureRecognizer*) recognizer
{
    [UIView animateWithDuration:0.75
                          delay:0.01
                        options:UIViewAnimationTransitionCurlUp animations:^(void){
                            self.center = CGPointMake(openPointCenter.x - OPENCENTERX,
                                                      openPointCenter.y);
    }completion:nil];
}
@end

4、viewController的调用

为了实现自定义视图的阴影，添加需要使用QuartzCore框架。在项目里添加QuartzCore框架后引入头文件。

- (void)viewDidLoad
{
    [super viewDidLoad];
   
    CGRect rect = CGRectMake(0, 0,
                             self.view.frame.size.width,
                             self.view.frame.size.height);
    NSLog(@"w:%f, h:%f", rect.size.width, rect.size.height);
    UIImageView *imageleft = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"left.png"]];
    imageleft.frame = rect;
    [self.view addSubview:imageleft];
   
    UIView *contentView = [[UIView alloc] initWithFrame:rect];
   
    UIImageView *imageView = [[UIImageView alloc]initWithImage:[UIImage imageNamed:@"index.png"]];
    imageView.frame = rect;
    [contentView addSubview:imageView];

    CustomView *customView = [[CustomView alloc] initWithView:contentView
                                                   parentView:self.view];
    [[customView layer] setShadowOffset:CGSizeMake(10, 10)];
    [[customView layer] setShadowRadius:20];
    [[customView layer] setShadowOpacity:1];
    [[customView layer] setShadowColor:[UIColor blackColor].CGColor];
   
    [self.view addSubview:customView];
}