iOS下拉、上拉刷新控件的封装

ios 封装下拉、上拉刷新控件，首先看下效果图：

简单阐述一下：自定义头部、尾部刷新视图，继承uiview，通过kvo监听scrollview的滑动，通过偏移量设置刷新状态，通过修改状态修改scrollview的滚动位置。建一个uiscrollview的分类，添加上拉、下拉刷新及回调的方法，可以让uitableview、uicollectionview直接调用。现在很多应用是在滑动到底部自动进行上拉加载超做，可以在scrollviewdidscroll这个代理方法中手动调用尾部刷新。

下面贴上主要相关代码：

控制器viewcontroller：

#import <uikit/uikit.h>

@interface viewcontroller : uiviewcontroller

@end

/*** ---------------分割线--------------- ***/

#import "viewcontroller.h"
#import "hwrefresh.h"

@interface viewcontroller ()<uitableviewdatasource, uitableviewdelegate>

@property (nonatomic, strong) nsmutablearray *array;
@property (nonatomic, strong) uitableview *tableview;
@property (nonatomic, assign) nsinteger page;

@end

@implementation viewcontroller

- (nsmutablearray *)array
{
 if (!_array) {
  _array = [nsmutablearray array];
 }

 return _array;
}

- (void)viewdidload {
 [super viewdidload];

 self.view.backgroundcolor = [uicolor blackcolor];
 self.page = 1;

 //模拟获取信息
 [self getinfo];

 //创建控件
 [self creatcontrol];

 //添加头部刷新
 [self addheaderrefresh];

 //添加尾部刷新
 [self addfooterrefresh];
}

- (void)getinfo
{
 nsarray *array = @[@"ios hero博客", @"ios hero博客", @"ios hero博客", @"ios hero博客", @"http://blog.csdn.net/hero_wqb"];
 dispatch_after(dispatch_time(dispatch_time_now, (int64_t)(2.0f * nsec_per_sec)), dispatch_get_main_queue(), ^{
  if (self.page == 1) {
   self.array = [nsmutablearray arraywitharray:array];
  }else{
   [self.array addobjectsfromarray:array];
  }
  [_tableview reloaddata];
  [_tableview headerendrefreshing];
  [_tableview footerendrefreshing];
  nslog(@"已经刷新好了");
 });
}

- (void)creatcontrol
{
 //列表视图
 _tableview = [[uitableview alloc] initwithframe:cgrectmake(20, 64, [[uiscreen mainscreen] bounds].size.width - 100, [[uiscreen mainscreen] bounds].size.height - 164) style:uitableviewstyleplain];
 _tableview.datasource = self;
 _tableview.delegate = self;
 [self.view addsubview:_tableview];
}

- (void)addheaderrefresh
{
 __weak typeof(self) weakself = self;
 [_tableview addheaderrefreshwithcallback:^{
  __strong typeof(weakself) strongself = weakself;
  strongself.page = 1;
  [strongself getinfo];
 }];
}

- (void)addfooterrefresh
{
 __weak typeof(self) weakself = self;
 [_tableview addfooterrefreshwithcallback:^{
  __strong typeof(weakself) strongself = weakself;
  strongself.page ++;
  [strongself getinfo];
 }];
}

#pragma mark - uitableviewdatasource
- (nsinteger)tableview:(uitableview *)tableview numberofrowsinsection:(nsinteger)section
{
 return self.array.count;
}

- (uitableviewcell *)tableview:(uitableview *)tableview cellforrowatindexpath:(nsindexpath *)indexpath
{
 static nsstring *identifier = @"refreshtest";
 uitableviewcell *cell = [tableview dequeuereusablecellwithidentifier:identifier];
 if (!cell) {
  cell = [[uitableviewcell alloc] initwithstyle:uitableviewcellstyledefault reuseidentifier:identifier];
 }
 cell.textlabel.text = [_array[indexpath.row] stringbyappendingstring:[nsstring stringwithformat:@"_%ld", indexpath.row]];

 return cell;
}

- (void)scrollviewdidscroll:(uiscrollview *)scrollview
{
 //滑动到底部自动刷新
 if (_tableview.contentsize.height > _tableview.frame.size.height && _tableview.contentoffset.y + _tableview.frame.size.height > _tableview.contentsize.height - 40 && _page < 50) {
  [_tableview footerbeginrefreshing];
 }
}

@end

刷新基类hwrefreshbaseview：

#import <uikit/uikit.h>

#define hwrefreshcontentoffset @"contentoffset"

typedef enum {
 hwrefreshstatenormal = 0, //普通状态
 hwrefreshstatepulling,  //释放即可刷新的状态
 hwrefreshstaterefreshing, //正在刷新中的状态
} hwrefreshstate;

@interface hwrefreshbaseview : uiview

@property (nonatomic, weak) uiscrollview *scrollview;
@property (nonatomic, copy) nsstring *pulltorefreshtext;
@property (nonatomic, copy) nsstring *releasetorefreshtext;
@property (nonatomic, copy) nsstring *refreshingtext;
@property (nonatomic, copy) void (^refreshingcallback)();
@property (nonatomic, assign) hwrefreshstate state;
@property (nonatomic, assign) uiedgeinsets scrollvieworiginalinset;

- (void)beginrefreshing;
- (void)endrefreshing;

@end

/*** ---------------分割线--------------- ***/

#import "hwrefreshbaseview.h"

#define khwrefreshviewheight 44.0f
#define kimagew 30.0f
#define klabelw 100.0f

@interface hwrefreshbaseview ()

@property (nonatomic, weak) uilabel *rlabel;
@property (nonatomic, weak) uiimageview *rimageview;

@end

@implementation hwrefreshbaseview

- (instancetype)initwithframe:(cgrect)frame
{
 frame.size.height = khwrefreshviewheight;
 if (self = [super initwithframe:frame]) {
  cgfloat imageh = 30.f;
  cgfloat labelh = 20.f;
  cgfloat imagex = ([uiscreen mainscreen].bounds.size.width - kimagew - klabelw) * 0.5;
  cgfloat imagey = (khwrefreshviewheight - imageh) * 0.5;
  cgfloat labely = (khwrefreshviewheight - labelh) * 0.5;

  //图片
  uiimageview *rimageview = [[uiimageview alloc] initwithframe:cgrectmake(imagex, imagey, kimagew, imageh)];
  rimageview.image = [uiimage imagenamed:@"refreshing.jpg"];
  [self addsubview:rimageview];
  self.rimageview = rimageview;

  //标签
  uilabel *rlabel = [[uilabel alloc] initwithframe:cgrectmake(cgrectgetmaxx(rimageview.frame), labely, klabelw, labelh)];
  rlabel.text = self.pulltorefreshtext;
  rlabel.font = [uifont systemfontofsize:14.0f];
  rlabel.textalignment = nstextalignmentcenter;
  [self addsubview:rlabel];
  self.rlabel = rlabel;
 }

 return self;
}

- (void)willmovetosuperview:(uiview *)newsuperview
{
 [super willmovetosuperview:newsuperview];

 //旧的父控件
 [self.superview removeobserver:self forkeypath:hwrefreshcontentoffset context:nil];

 //新的父控件
 if (newsuperview) {
  [newsuperview addobserver:self forkeypath:hwrefreshcontentoffset options:nskeyvalueobservingoptionnew context:nil];

  //记录uiscrollview
  _scrollview = (uiscrollview *)newsuperview;

  //记录uiscrollview最开始的contentinset
  _scrollvieworiginalinset = _scrollview.contentinset;
 }

 //居中显示图片、提示信息
 cgrect temframe = _rimageview.frame;
 temframe.origin.x = (newsuperview.frame.size.width - kimagew - klabelw) * 0.5;
 _rimageview.frame = temframe;

 cgrect tf = _rlabel.frame;
 tf.origin.x = cgrectgetmaxx(_rimageview.frame);
 _rlabel.frame = tf;
}

- (void)setpulltorefreshtext:(nsstring *)pulltorefreshtext
{
 _pulltorefreshtext = pulltorefreshtext;

 self.rlabel.text = pulltorefreshtext;
}

- (void)setstate:(hwrefreshstate)state
{
 if (_state == state) return;

 switch (state) {
  case hwrefreshstatenormal: {
   [self stopanimating];
   self.rlabel.text = self.pulltorefreshtext;
   break;
  }

  case hwrefreshstatepulling: {
   self.rlabel.text = self.releasetorefreshtext;
   break;
  }

  case hwrefreshstaterefreshing: {
   [self startanimating];
   self.rlabel.text = self.refreshingtext;
   if (self.refreshingcallback) self.refreshingcallback();
   break;
  }

  default:
   break;
 }

 _state = state;
}

//开始刷新
- (void)beginrefreshing
{
 self.state = hwrefreshstaterefreshing;
}

//结束刷新
- (void)endrefreshing
{
 self.state = hwrefreshstatenormal;
}

//开始动画
- (void)startanimating
{
 nsmutablearray *array = [nsmutablearray array];
 for (int i = 0; i < 2; i++) {
  nsstring *imagename = [nsstring stringwithformat:@"refreshing%02d.jpg", i + 1];
  uiimage *image = [uiimage imagenamed:imagename];
  [array addobject:image];
 }

 [_rimageview setanimationimages:array];
 [_rimageview setanimationduration:0.3f];
 [_rimageview startanimating];
}

//结束动画
- (void)stopanimating
{
 if (_rimageview.isanimating) {
  [_rimageview stopanimating];
  [_rimageview performselector:@selector(setanimationimages:) withobject:nil afterdelay:0];
 }
}

@end

头部刷新hwrefreshheader：

#import "hwrefreshbaseview.h"

@interface hwrefreshheader : hwrefreshbaseview

+ (instancetype)header;

@end

/*** ---------------分割线--------------- ***/

#import "hwrefreshheader.h"

@implementation hwrefreshheader

+ (instancetype)header
{
 return [[hwrefreshheader alloc] init];
}

- (instancetype)initwithframe:(cgrect)frame
{
 if (self = [super initwithframe:frame]) {
  self.pulltorefreshtext = @"下拉即可刷新";
  self.releasetorefreshtext = @"释放即可刷新";
  self.refreshingtext = @"刷新中...";
 }

 return self;
}

- (void)willmovetosuperview:(uiview *)newsuperview
{
 [super willmovetosuperview:newsuperview];

 //设置自己的位置和尺寸
 cgrect frame = self.frame;
 frame.origin.y = - self.frame.size.height;
 self.frame = frame;
}


- (void)observevalueforkeypath:(nsstring *)keypath ofobject:(id)object change:(nsdictionary *)change context:(void *)context
{
 //不能跟用户交互或正在刷新就直接返回
 if (!self.userinteractionenabled || self.alpha <= 0.01 || self.hidden || self.state == hwrefreshstaterefreshing) return;

 //根据偏移量设置相应状态
 if ([keypath isequaltostring:hwrefreshcontentoffset]) {
  [self setstatewithcontentoffset];
 }
}

- (void)setstatewithcontentoffset
{
 //当前的contentoffset
 cgfloat currentoffsety = self.scrollview.contentoffset.y;

 //头部控件刚好出现的offsety
 cgfloat happenoffsety = - self.scrollvieworiginalinset.top;

 //如果是向上滚动到看不见头部控件，直接返回
 if (currentoffsety >= happenoffsety) return;

 //滑动时
 if (self.scrollview.isdragging) {
  //普通状态和即将刷新状态的临界点
  cgfloat normaltopullingoffsety = happenoffsety - self.frame.size.height;

  //转为即将刷新状态
  if (self.state == hwrefreshstatenormal && currentoffsety < normaltopullingoffsety) {
   self.state = hwrefreshstatepulling;

  //转为普通状态
  }else if (self.state == hwrefreshstatepulling && currentoffsety >= normaltopullingoffsety) {
   self.state = hwrefreshstatenormal;
  }

 //松手时，如果是松开就可以进行刷新的状态，则进行刷新
 }else if (self.state == hwrefreshstatepulling) {
  self.state = hwrefreshstaterefreshing;
 }
}

- (void)setstate:(hwrefreshstate)state
{
 //若状态未改变，直接返回
 if (self.state == state) return;

 //保存旧状态
 hwrefreshstate oldstate = self.state;

 //调用父类方法
 [super setstate:state];

 switch (state) {
  case hwrefreshstatenormal: {
   //如果由刷新状态返回到普通状态
   if (oldstate == hwrefreshstaterefreshing) {
    [uiview animatewithduration:0.25f animations:^{
     uiedgeinsets inset = self.scrollview.contentinset;
     inset.top -= self.frame.size.height;
     self.scrollview.contentinset = inset;
    }];
   }
   break;
  }

  case hwrefreshstatepulling: {
   break;
  }

  case hwrefreshstaterefreshing: {
   //执行动画
   [uiview animatewithduration:0.25f animations:^{
    cgfloat top = self.scrollvieworiginalinset.top + self.frame.size.height;

    //增加滚动区域
    uiedgeinsets inset = self.scrollview.contentinset;
    inset.top = top;
    self.scrollview.contentinset = inset;

    //设置滚动位置
    cgpoint offset = self.scrollview.contentoffset;
    offset.y = - top;
    self.scrollview.contentoffset = offset;
   }];
   break;
  }

  default:
   break;
 }

 self.state = state;
}

@end

分类uiscrollview+hwrefresh：

#import <uikit/uikit.h>

@interface uiscrollview (hwrefresh)

//添加下拉刷新回调
- (void)addheaderrefreshwithcallback:(void (^)())callback;

//让下拉刷新控件停止刷新
- (void)headerendrefreshing;

//添加上拉刷新回调
- (void)addfooterrefreshwithcallback:(void (^)())callback;

//让上拉刷新控件开始刷新
- (void)footerbeginrefreshing;

//让上拉刷新控件停止刷新
- (void)footerendrefreshing;

@end

/*** ---------------分割线--------------- ***/

#import "uiscrollview+hwrefresh.h"
#import "hwrefreshheader.h"
#import "hwrefreshfooter.h"
#import <objc/runtime.h>

@interface uiscrollview ()

@property (nonatomic, weak) hwrefreshheader *header;
@property (weak, nonatomic) hwrefreshfooter *footer;

@end

@implementation uiscrollview (hwrefresh)

static char hwrefreshheaderkey;
static char hwrefreshfooterkey;

- (void)setheader:(hwrefreshheader *)header
{
 [self willchangevalueforkey:@"hwrefreshheaderkey"];
 objc_setassociatedobject(self, &hwrefreshheaderkey, header, objc_association_assign);
 [self didchangevalueforkey:@"hwrefreshheaderkey"];
}

- (hwrefreshheader *)header
{
 return objc_getassociatedobject(self, &hwrefreshheaderkey);
}

- (void)setfooter:(hwrefreshfooter *)footer
{
 [self willchangevalueforkey:@"hwrefreshfooterkey"];
 objc_setassociatedobject(self, &hwrefreshfooterkey, footer, objc_association_assign);
 [self didchangevalueforkey:@"hwrefreshfooterkey"];
}

- (hwrefreshfooter *)footer
{
 return objc_getassociatedobject(self, &hwrefreshfooterkey);
}

- (void)addheaderrefreshwithcallback:(void (^)())callback
{
 if (!self.header) {
  hwrefreshheader *header = [hwrefreshheader header];
  [self addsubview:header];
  self.header = header;
 }

 self.header.refreshingcallback = callback;
}

- (void)headerendrefreshing
{
 [self.header endrefreshing];
}

- (void)addfooterrefreshwithcallback:(void (^)())callback
{
 if (!self.footer) {
  hwrefreshfooter *footer = [hwrefreshfooter footer];
  [self addsubview:footer];
  self.footer = footer;
 }

 self.footer.refreshingcallback = callback;
}

- (void)footerbeginrefreshing
{
 [self.footer beginrefreshing];
}

- (void)footerendrefreshing
{
 [self.footer endrefreshing];
}

@end

demo下载链接

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原文链接：https://blog.csdn.net/hero_wqb/article/details/73554721