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本文实例为大家分享了ios多线程实现多图下载功能的具体代码，供大家参考，具体内容如下
一.模型文件代码如下
// xmgapp.h #import <foundation/foundation.h> @interface xmgapp : nsobject /** app的名称 */ @property (nonatomic, strong) nsstring *name; /** app的图片的url地址 */ @property (nonatomic, strong) nsstring *icon; /** app的下载量 */ @property (nonatomic, strong) nsstring *download; +(instancetype)appwithdict:(nsdictionary *)dict; @end
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// xmgapp.m
#import "xmgapp.h"
@implementation xmgapp
+(instancetype)appwithdict:(nsdictionary *)dict
{
xmgapp *appm = [[xmgapp alloc]init];
//kvc
[appm setvaluesforkeyswithdictionary:dict];
return appm;
}
@end
控制器.m代码如下:
// viewcontroller.m
#import "viewcontroller.h"
#import "xmgapp.h"
@interface viewcontroller ()
/** tableview的数据源 */
@property (nonatomic, strong) nsarray *apps;
/** 内存缓存 */
@property (nonatomic, strong) nsmutabledictionary *images;
/** 队列 */
@property (nonatomic, strong) nsoperationqueue *queue;
/** 操作缓存 */
@property (nonatomic, strong) nsmutabledictionary *operations;
@end
@implementation viewcontroller
#pragma mark ----------------------
#pragma mark lazy loading
-(nsoperationqueue *)queue
{
if (_queue == nil) {
_queue = [[nsoperationqueue alloc]init];
//设置最大并发数
_queue.maxconcurrentoperationcount = 5;
}
return _queue;
}
-(nsmutabledictionary *)images
{
if (_images == nil) {
_images = [nsmutabledictionary dictionary];
}
return _images;
}
-(nsarray *)apps
{
if (_apps == nil) {
//字典数组
nsarray *arraym = [nsarray arraywithcontentsoffile:[[nsbundle mainbundle]pathforresource:@"apps.plist" oftype:nil]];
//字典数组---->模型数组
nsmutablearray *arrm = [nsmutablearray array];
for (nsdictionary *dict in arraym) {
[arrm addobject:[xmgapp appwithdict:dict]];
}
_apps = arrm;
}
return _apps;
}
-(nsmutabledictionary *)operations
{
if (_operations == nil) {
_operations = [nsmutabledictionary dictionary];
}
return _operations;
}
#pragma mark ----------------------
#pragma mark uitableviewdatasource
-(nsinteger)numberofsectionsintableview:(uitableview *)tableview
{
return 1;
}
-(nsinteger)tableview:(uitableview *)tableview numberofrowsinsection:(nsinteger)section
{
return self.apps.count;
}
-(uitableviewcell *)tableview:(uitableview *)tableview cellforrowatindexpath:(nsindexpath *)indexpath
{
static nsstring *id = @"app";
//1.创建cell
uitableviewcell *cell = [tableview dequeuereusablecellwithidentifier:id];
//2.设置cell的数据
//2.1 拿到该行cell对应的数据
xmgapp *appm = self.apps[indexpath.row];
//2.2 设置标题
cell.textlabel.text = appm.name;
//2.3 设置子标题
cell.detailtextlabel.text = appm.download;
//2.4 设置图标
//先去查看内存缓存中该图片时候已经存在,如果存在那么久直接拿来用,否则去检查磁盘缓存
//如果有磁盘缓存,那么保存一份到内存,设置图片,否则就直接下载
//1)没有下载过
//2)重新打开程序
uiimage *image = [self.images objectforkey:appm.icon];
if (image) {
cell.imageview.image = image;
nslog(@"%zd处的图片使用了内存缓存中的图片",indexpath.row) ;
}else
{
//保存图片到沙盒缓存
nsstring *caches = [nssearchpathfordirectoriesindomains(nscachesdirectory, nsuserdomainmask, yes) lastobject];
//获得图片的名称,不能包含/
nsstring *filename = [appm.icon lastpathcomponent];
//拼接图片的全路径
nsstring *fullpath = [caches stringbyappendingpathcomponent:filename];
//检查磁盘缓存
nsdata *imagedata = [nsdata datawithcontentsoffile:fullpath];
//废除
imagedata = nil;
if (imagedata) {
uiimage *image = [uiimage imagewithdata:imagedata];
cell.imageview.image = image;
nslog(@"%zd处的图片使用了磁盘缓存中的图片",indexpath.row) ;
//把图片保存到内存缓存
[self.images setobject:image forkey:appm.icon];
// nslog(@"%@",fullpath);
}else
{
//检查该图片时候正在下载,如果是那么久什么都捕捉,否则再添加下载任务
nsblockoperation *download = [self.operations objectforkey:appm.icon];
if (download) {
}else
{
//先清空cell原来的图片
cell.imageview.image = [uiimage imagenamed:@"snip20160221_306"];
download = [nsblockoperation blockoperationwithblock:^{
nsurl *url = [nsurl urlwithstring:appm.icon];
nsdata *imagedata = [nsdata datawithcontentsofurl:url];
uiimage *image = [uiimage imagewithdata:imagedata];
nslog(@"%zd--下载---",indexpath.row);
//容错处理
if (image == nil) {
[self.operations removeobjectforkey:appm.icon];
return ;
}
//演示网速慢的情况
//[nsthread sleepfortimeinterval:3.0];
//把图片保存到内存缓存
[self.images setobject:image forkey:appm.icon];
//nslog(@"download---%@",[nsthread currentthread]);
//线程间通信
[[nsoperationqueue mainqueue] addoperationwithblock:^{
//cell.imageview.image = image;
//刷新一行
[self.tableview reloadrowsatindexpaths:@[indexpath] withrowanimation:uitableviewrowanimationleft];
//nslog(@"ui---%@",[nsthread currentthread]);
}];
//写数据到沙盒
[imagedata writetofile:fullpath atomically:yes];
//移除图片的下载操作
[self.operations removeobjectforkey:appm.icon];
}];
//添加操作到操作缓存中
[self.operations setobject:download forkey:appm.icon];
//添加操作到队列中
[self.queue addoperation:download];
}
}
}
//3.返回cell
return cell;
}
-(void)didreceivememorywarning
{
[self.images removeallobjects];
//取消队列中所有的操作
[self.queue cancelalloperations];
}
//1.ui很不流畅 --- > 开子线程下载图片
//2.图片重复下载 ---> 先把之前已经下载的图片保存起来(字典)
//内存缓存--->磁盘缓存
//3.图片不会刷新--->刷新某行
//4.图片重复下载(图片下载需要时间,当图片还未完全下载之前,又要重新显示该图片)
//5.数据错乱 ---设置占位图片
/*
documents:会备份,不允许
libray
preferences:偏好设置 保存账号
caches:缓存文件
tmp:临时路径(随时会被删除)
*/
@end
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持移动技术网。
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