【移动应用开发技术】怎么在iOS中利用多线程实现多图下载功能

【移动应用开发技术】怎么在iOS中利用多线程实现多图下载功能

这篇文章将为大家详细讲解有关怎么在iOS中利用多线程实现多图下载功能，文章内容质量较高，因此在下分享给大家做个参考，希望大家阅读完这篇文章后对相关知识有一定的了解。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//

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];