小编Way*_*yne的帖子

正如文档所说" 您确定可选项确实包含值,您可以通过添加感叹号(!)来访问其基础值 "

那么为什么UIViewController使用init方法呢

init(nibName nibName: String!,bundle nibBundle: NSBundle!)

并告诉我" 如果指定nil,则nibName属性设置为nil. "

为什么init(nibName nibName: String?,bundle nibBundle: NSBundle?)不用呢？

我对此很困惑.

我想使用__block变量来获取块中的值.但是当阻塞时,__block变量似乎是零.为什么会这样？

    NSString *fileName = [Tools MD5Encode:url];
    __block NSString *filePath = nil;
    [fileList enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        NSString *aFileName = obj;
        if ([aFileName isEqualToString:fileName]) {
            NSString *path = [VERSIONS_INFO_DATA_DIRECTORY stringByAppendingPathComponent:aFileName];
            filePath = path;
            NSLog(@"filePath1 %@", filePath);
            *stop = YES;
        }
    }];
    //NSLog(@"filePath2 %@", filePath);
    //filePath seems to be nil
    return filePath;

当我将代码更改为[路径复制]时,它可以工作.但我不知道这是不是一个好主意.任何决定？

    NSString *fileName = [Tools MD5Encode:url];
    __block NSString *filePath = nil;
    [fileList enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL *stop) {
        NSString *aFileName = obj;
        if ([aFileName isEqualToString:fileName]) { …

我想使用AFNetwork下载多个文件,但我不知道如何实现这个？如您所见,我创建了一个操作数组并在其中添加了3个任务

NSMutableArray *operations = [NSMutableArray array];
NSArray *requestArray = @[ @"...task1.zip", @"task2.zip", @"task3.zip" ];
for (int i = 0; i < 3; i++) {
    NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:[requestArray objectAtIndex:i]]];
    AFHTTPRequestOperation *operation = [[AFHTTPRequestOperation alloc] initWithRequest:request];

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *path = [[paths objectAtIndex:0] stringByAppendingPathComponent:[[requestArray objectAtIndex:i] lastPathComponent]];
    operation.outputStream = [NSOutputStream outputStreamToFileAtPath:path append:NO];

    [operation setCompletionBlockWithSuccess:^(AFHTTPRequestOperation *operation, id responseObject) {
        NSLog(@"Successfully downloaded file to %@", path);
    } failure:^(AFHTTPRequestOperation *operation, NSError *error) {
        NSLog(@"Error: %@", error);
    }];

    [operation setDownloadProgressBlock:^(NSUInteger …