iOS实现左右拖动抽屉效果

本文实例介绍了ios实现左右拖动抽屉效果，具体内容如下

利用了触摸事件滑动 touchesmoved: 来触发左右视图的出现和消失 利用loadview方法中添加view 在self.view载入前就把 左右中view都设置好frame 每一个方法都由单独的功能。

#import "darwviewcontroller.h"
@interface darwviewcontroller ()
@property (nonatomic, weak) uiview *leftview;
@property (nonatomic, weak) uiview *rightview;
@property (nonatomic, weak) uiview *mainview;
/**
 * 动画是否进行
 */
@property (nonatomic ,assign) bool animating;
 
@end
 
@implementation darwviewcontroller
- (void)viewdidload {
  [super viewdidload];
}
 
 
-(void)loadview
{
  self.view = [[uiview alloc]initwithframe:[uiscreen mainscreen].bounds];
  //左边view
  uiview *leftview = [[uiview alloc]initwithframe:self.view.frame];
  [self.view addsubview:leftview];
  leftview.backgroundcolor= [uicolor redcolor];
  self.leftview = leftview;
   
  //右边view
  uiview *rightview = [[uiview alloc]initwithframe:self.view.frame];
  [self.view addsubview:rightview];
  rightview.backgroundcolor= [uicolor bluecolor];
  self.rightview = rightview;
   
  //主页面
  uiview *mainview = [[uiview alloc]initwithframe:self.view.frame];
  [self.view addsubview:mainview];
  mainview.backgroundcolor= [uicolor yellowcolor];
  self.mainview = mainview;
   
   
  //kvo监听
  [self.mainview addobserver:self forkeypath:@"frame" options:nskeyvalueobservingoptionnew context:nil];
}
/**
 * kvo回调方法 当mainview frame值改变时触发
 *
 * @param keypath <#keypath description#>
 * @param object <#object description#>
 * @param change <#change description#>
 * @param context <#context description#>
 */
-(void)observevalueforkeypath:(nsstring *)keypath ofobject:(id)object change:(nsdictionary<nsstring *,id> *)change context:(void *)context
{
  if (self.animating) return; //如果mainview正在动画 就不执行
  if (self.mainview.frame.origin.x > 0 )
  {
    //x > 0 就隐藏右边view 显示左边view
    self.rightview.hidden = yes;
    self.leftview.hidden = no;
  }
  else if (self.mainview.frame.origin.x < 0)
  {
    //x < 0 就隐藏左边view 显示右边view
    self.leftview.hidden = yes;
    self.rightview.hidden = no;
  }
}
#pragma mark -- 触摸事件
-(void)touchesmoved:(nsset<uitouch *> *)touches withevent:(uievent *)event
{
  //获得触摸对象
  uitouch *touch = [touches anyobject];
   
  //获得当前触摸点
  cgpoint currentpoint = [touch locationinview:self.view];
  //获得上一个触摸点
  cgpoint previouspoint = [touch previouslocationinview:self.view];
   
  //计算x方向的偏移量
  cgfloat offsetx = currentpoint.x - previouspoint.x;
//  根据x的偏移量计算y的偏移量
  self.mainview.frame = [self rectwithoffsetx:offsetx];
   
}
#define screenw [uiscreen mainscreen].bounds.size.width
#define screenh [uiscreen mainscreen].bounds.size.height
/**
 * 计算主视图的frame
 *
 * @param offsetx x的偏移量
 *
 * @return 偏移后新的frame
 */
- (cgrect ) rectwithoffsetx:(cgfloat )offsetx
{
  //y轴的偏移量
  cgfloat offsety = (screenh *1/5) * (offsetx/screenw);
   
  //比例 ：（用于宽高的缩放）
  cgfloat scale = (screenh - offsety *2) / screenh;
  if (self.mainview.frame.origin.x < 0 )
  {
    //如果x是负数 及左边view要显示
    //比例就要设为比1小
    scale = 2 - scale;
  }
  //获取当前mainview的frame
  cgrect frame = self.mainview.frame;
   
  //重新设置mainview的frame值
  frame.size.width = frame.size.width *scale >screenw ? screenw : frame.size.width *scale;
   
  frame.size.height = frame.size.height *scale >screenh ? screenh :frame.size.height *scale;
   
  frame.origin.x += offsetx;
  frame.origin.y =(screenh - frame.size.height)*0.5;
  //返回偏移后新的frame
  return frame;
}
#define maxrightx (screenw *0.8)
#define maxleftx (-screenw *0.6)
-(void)touchesended:(nsset<uitouch *> *)touches withevent:(uievent *)event
{
  cgfloat targetx = 0;
  //如果松手的那一下 当前mainview的x大于屏幕的一半
  if (self.mainview.frame.origin.x > screenw * 0.5)
  {
    //向右边定位
    targetx = maxrightx;
  }
  //如果松手的那一下 当前mainview的最大x值小于屏幕的一半
  else if (cgrectgetmaxx(self.mainview.frame) < screenw *0.5)
  {
    //向左边定位
    targetx = maxleftx;
  }
   
  //计算偏移量
  cgfloat offsetx = targetx -self.mainview.frame.origin.x;
   
  self.animating = yes;
   
  [uiview animatewithduration:0.4 animations:^{
    if (targetx == 0)
    {
      //如果targetx==0 复位
      self.mainview.frame = self.view.frame;
    }
    else
    {
      //如果targetx != 0 那就到指定位置
      self.mainview.frame = [self rectwithoffsetx:offsetx];
    }
  } completion:^(bool finished) {
    self.animating = no;
  }];
     
}
@end

以上就是本文的全部内容，希望对大家的学习有所帮助。