多线程技术（三）

最新推荐文章于 2025-01-10 14:28:23 发布

Jintao_Lmorning

最新推荐文章于 2025-01-10 14:28:23 发布

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分类专栏： iOS 编程 MODEL-STORAGE 文章标签： iOS

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[Demo01_GCD_plist]

TRTableViewController.m

<span style="font-size:14px;">#import "TRTableViewController.h"
#import "TRDataManager.h"
#import "TRAlbum.h"
#import "TRTableViewCell.h"

@interface TRTableViewController ()

@property (nonatomic, strong) NSArray *albumsArray;
//存储下载好的图片的数据
@property (nonatomic, strong) NSMutableDictionary *imageMutableDic;

@end

@implementation TRTableViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.albumsArray = [TRDataManager getAllAlbums];
    //初始化可变字典
    self.imageMutableDic = [NSMutableDictionary dictionary];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    return self.albumsArray.count;
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    TRTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"albumCell"];
    // Configure the cell...
    //singer/name
    //数据源
    TRAlbum *album = self.albumsArray[indexPath.row];
    cell.textLabel.text = album.singer;
    cell.detailTextLabel.text = album.name;
    //赋值一个占位图片(两个lable不会最左边排列)
    cell.imageView.image = [UIImage imageNamed:@"s0"];
    
    //实现图片缓存的原理
    //判断字典中有没有
    NSData *readData = self.imageMutableDic[album.poster];
    if (readData) {
        //字典中有图片数据;显示
        cell.imageView.image = [UIImage imageWithData:readData];
    } else {
        //字典中没有；判断沙盒中有没有
        NSString *filePath = [self generateFilePath:album.poster];
        NSData *dataFromFile = [NSData dataWithContentsOfFile:filePath];
        if (dataFromFile) {
            //沙盒中有图片数据；显示
            cell.imageView.image = [UIImage imageWithData:dataFromFile];
        } else {
            //字典没有；沙盒没有；开始下载图片
            [self downloadImageWithCell:cell withAlbum:album];
        }
    }
    
    
    //下载图片
//    [self downloadImageWithCell:cell withAlbum:album];
    
    return cell;
}

- (void)downloadImageWithCell:(TRTableViewCell *)cell withAlbum:(TRAlbum *)album {
    dispatch_async(dispatch_get_global_queue(0, 0), ^{
        NSURL *imageURL = [NSURL URLWithString:album.poster];
        NSData *imageData = [NSData dataWithContentsOfURL:imageURL];
        if (imageData) {
            //存到字典中
            self.imageMutableDic[album.poster] = imageData;
            //存到沙盒文件中(文件所在的整个路径)
            NSString *filePath = [self generateFilePath:album.poster];
            [imageData writeToFile:filePath atomically:YES];
        }
        //返回主线程更新
        dispatch_async(dispatch_get_main_queue(), ^{
            cell.imageView.image = [UIImage imageWithData:imageData];
            
//            //刷新
//            [self.tableView reloadData];
        });
        
    });
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
    return 80;
}


- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
//    NSLog(@"dfafdsagagdg");
}

//返回已经拼接好的文件的路径
- (NSString *)generateFilePath:(NSString *)imageURLStr {
    //找Caches路径
    NSString *cachesPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) firstObject];
    //获取url最后一部分:s2874587.jpg
    //https://img1.doubanio.com/mpic/s2874587.jpg
    NSString *imageName = [imageURLStr lastPathComponent];
    return [cachesPath stringByAppendingPathComponent:imageName];
}
</span>

TRTableViewCell.m

<span style="font-size:14px;">- (void)setSelected:(BOOL)selected animated:(BOOL)animated {
    //当点击cell的时候，会自动触发这个方法；父类自动的重新设置cell的imageView的frame
//    [super setSelected:selected animated:animated];
    //自定义cell选中的颜色
    if (selected) {
        //选中的颜色
        [self setBackgroundColor:[UIColor colorWithRed:245.0/255 green:245.0/255 blue:245.0/255 alpha:1]];
    } else {
        //默认颜色
        [self setBackgroundColor:[UIColor whiteColor]];
    }
    
    
}</span>

TRAlbum.h

<span style="font-size:14px;">/** 歌曲名字 */
@property (nonatomic, copy) NSString *name;
/** 歌手名字 */
@property (nonatomic, copy) NSString *singer;
/** 专辑图片URL */
@property (nonatomic, copy) NSString *poster;</span>

TRDataManager.m

<span style="font-size:14px;">static NSArray *_albumsArray = nil;//只从文件中读一次
+ (NSArray *)getAllAlbums {
    if (!_albumsArray) {
        _albumsArray = [[self alloc] getAllAlbums];
    }
    return _albumsArray;
}

- (NSArray *)getAllAlbums {
    //plist路径
    NSString *plistPath = [[NSBundle mainBundle] pathForResource:@"albums.plist" ofType:nil];
    //取plist数据
    NSArray *plistArray = [NSArray arrayWithContentsOfFile:plistPath];
    //for循环将字典转成TRAlbum
    NSMutableArray *mutableArray = [NSMutableArray array];
    for (NSDictionary *albumDic in plistArray) {
        //NSDictionary -> Album
        TRAlbum *album = [TRAlbum new];
        [album setValuesForKeysWithDictionary:albumDic];
        [mutableArray addObject:album];
    }
    return [mutableArray copy];
}
</span>

[Demo02_GCD_SDWebImage]

TRTableViewController.m

<span style="font-size:14px;">static void *imageViewFrameKey = &imageViewFrameKey;
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    TRTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"albumCell"];
    // Configure the cell...
    //singer/name
    //数据源
    TRAlbum *album = self.albumsArray[indexPath.row];
    cell.textLabel.text = album.singer;
    cell.detailTextLabel.text = album.name;
    //赋值一个占位图片(两个lable不会最左边排列)
//    cell.imageView.image = [UIImage imageNamed:@"s0"];
    
    //使用KVO方式监听cell的frame变化
    [cell.imageView addObserver:self forKeyPath:@"frame" options:NSKeyValueObservingOptionNew context:imageViewFrameKey];
    
    //实现图片缓存的原理
    [cell.imageView sd_setImageWithURL:[NSURL URLWithString:album.poster] placeholderImage:[UIImage imageNamed:@"s0"]];
    
    return cell;
}
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if (context == imageViewFrameKey) {
        NSLog(@"====%@", change[@"new"]);
        
        //此时监听到imageView的frame发生变化，改成自定义的frame值
        UIImageView *imageView = (UIImageView *)object;
        CGRect newRect = CGRectMake(20, 9, 60, 60);
        if (!CGRectEqualToRect(imageView.frame, newRect)) {
            imageView.frame = newRect;
        }
    } else {
        [super observeValueForKeyPath:keyPath ofObject:object change:change context:context];
    }
}
</span>

[Demo03_Group]

<span style="font-size:14px;">// 1.创建一个group组对象
    dispatch_group_t group = dispatch_group_create();
    // 2.添加两个任务(5s； 8s);全局队列+异步执行
    dispatch_group_async(group, dispatch_get_global_queue(0, 0), ^{
        //子线程执行
        NSLog(@"下载图片一开始");
        [NSThread sleepForTimeInterval:5];
        NSLog(@"下载图片一结束");
    });
    dispatch_group_async(group, dispatch_get_global_queue(0, 0), ^{
        NSLog(@"下载图片二开始");
        [NSThread sleepForTimeInterval:8];
        NSLog(@"下载图片二结束");
    });
    // 3.GCD中通知的方法，告诉两个任务完毕
    dispatch_group_notify(group, dispatch_get_global_queue(0, 0), ^{
        //子线程
        NSLog(@"两个图片下载完毕，上传开始...");
        //回到主线程
        dispatch_async(dispatch_get_main_queue(), ^{
            NSLog(@"开始更新新界面...");
        });
    });
</span>

[Demo04_Singleton]

<span style="font-size:14px;">//调用线程不安全单例方法
    //需求：使用shared方法和使用alloc两种方法返回的对象都是同一个(更加严格单例方式)
    
    //调用线程安全的严格的单例方法
    //shared+alloc+copy
    TRDataManager *firstDataManager = [TRDataManager sharedDataManagerBySafe];
    TRDataManager *secondDataManager = [[TRDataManager alloc] init];
    TRDataManager *thirdDataManager = [secondDataManager copy];
    NSLog(@"first:%p; second:%p; third:%p", firstDataManager, secondDataManager, thirdDataManager);
</span>

DataManager.h

<span style="font-size:14px;">//返回单例对象，使用线程不安全方式
+ (instancetype)sharedDataManagerByUnsafe;

//返回单例对象，使用线程安全方式(GCD一次性任务)
+ (instancetype)sharedDataManagerBySafe;</span>

DataManager.m

<span style="font-size:14px;">static DataManager *_dataManagerByUnsafe = nil;
+ (instancetype)sharedDataManagerByUnsafe {
    if (!_dataManagerByUnsafe) {
        _dataManagerByUnsafe = [[DataManager alloc] init];
    }
    return _dataManagerByUnsafe;
}

////////////////////////////////////

static DataManager *_dataManagerBySafe = nil;
+ (instancetype)sharedDataManagerBySafe {
    //1.创建一个静态的一次性任务对象
    static dispatch_once_t onceToken;
    //2.调用一次性任务方法
    dispatch_once(&onceToken, ^{
        //创建单例对象
        _dataManagerBySafe = [[DataManager alloc] init];
    });
    //3.返回单例对象
    return _dataManagerBySafe;
}
//重写alloc方法; 或者重写allocWithZone
+ (instancetype)allocWithZone:(struct _NSZone *)zone {
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _dataManagerBySafe = [super allocWithZone:zone];
    });
    return _dataManagerBySafe;
}

//当copy当前类型对象时候，返回唯一的单例对象
- (id)copyWithZone:(NSZone *)zone {
    return _dataManagerBySafe;
}

//////////////////////////////
//创建单例的方式三
static DataManager *_dataManagerByInit = nil;
+ (void)initialize {
    if (self == [DataManager class]) {
        //初始化操作;一定能保证只调用一次+线程安全的
        _dataManagerByInit = [[DataManager alloc] init];
    }
}
+ (instancetype)sharedDataManagerByInit {
    return _dataManagerByInit;
}
</span>