iOS多线程实现多图下载功能
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, span) NSString *name;
/** APP的图片的url地址 */
@property (nonatomic, span) NSString *icon;
/** APP的下载量 */
@property (nonatomic, span) NSString *download;
+(instancetype)appWithDict:(NSDictionary *)dict;
@end
// 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, span) NSArray *apps;
/** 内存缓存 */
@property (nonatomic, span) NSMutableDictionary *images;
/** 队列 */
@property (nonatomic, span) NSOperationQueue *queue;
/** 操作缓存 */
@property (nonatomic, span) 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
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