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：
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#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
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刷新基类hwrefreshbaseview：
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#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
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头部刷新hwrefreshheader：
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#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
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分类uiscrollview+hwrefresh：
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#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
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写博客的初心是希望大家共同交流成长，博主水平有限难免有偏颇之处，欢迎批评指正。
原文链接：https://blog.csdn.net/hero_wqb/article/details/73554721