如何将图像保存到我的应用程序的tmp目录？

Question

为什么如果我NSTemporaryDirectory用来保存我的图像,图像就会保存到

在/ var /文件夹/ OG/oGrLHcAUEQubd3CBTs-1zU +++ TI/-Tmp- /

而不是

/ Users/MyMac/Library/Application Support/iPhone Simulator/4.3.2/Applications/A685734E-36E9-45DD-BBE7-0A46F8F91DAF/tmp

这是我的代码:

-(NSString *)tempPath
{
    return NSTemporaryDirectory();
}

-(void) saveMyFoto
{
    NSString *urlNahledu = [NSString stringWithFormat:@"%@%@%@",@"http://www.czechmat.cz", urlFotky,@"_100x100.jpg"];
    NSLog(@"%@", urlNahledu);


    UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:urlNahledu]]];

    NSData *data = [NSData dataWithData:UIImageJPEGRepresentation(image, 0.8f)];

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

    NSLog(@"%@    %@", paths, [self tempPath]);

    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *localFilePath = [documentsDirectory stringByAppendingPathComponent:@"pkm.jpg"];

    [data writeToFile:localFilePath atomically:YES];
}

Answer 1

这是首选方法,它使用URL来直接获取tmp目录的链接,然后返回该目录的文件URL(pkm.jpg):

Swift 4.1

let url = URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)
    .appendingPathComponent("pkm", isDirectory: false)
    .appendingPathExtension("jpg")

// Then write to disk
if let data = UIImageJPEGRepresentation(image, 0.8) {
    do {
        try data.write(to: url)
    } catch {
        print("Handle the error, i.e. disk can be full")
    }
}

Swift 3.1

let tmpURL = try! URL(fileURLWithPath: NSTemporaryDirectory(), isDirectory: true)
                    .appendingPathComponent("pkm")
                    .appendingPathExtension("jpg")
print("Filepath: \(tmpURL)")

请注意,未处理可能的错误!

Swift 2.0

let tmpDirURL = NSURL.fileURLWithPath(NSTemporaryDirectory(), isDirectory: true)
let fileURL = tmpDirURL.URLByAppendingPathComponent("pkm").URLByAppendingPathExtension("jpg")
print("FilePath: \(fileURL.path)")

Objective-C的

NSURL *tmpDirURL = [NSURL fileURLWithPath:NSTemporaryDirectory() isDirectory:YES];
NSURL *fileURL = [[tmpDirURL URLByAppendingPathComponent:@"pkm"] URLByAppendingPathExtension:@"jpg"];
NSLog(@"fileURL: %@", [fileURL path]);

请注意,某些方法仍然以字符串形式请求路径,然后使用它将路径作为字符串[fileURL path]返回(如上面NSLog中所示).升级当前App时文件夹中的所有文件:

<Application_Home>/Documents/
<Application_Home>/Library/

保证保留旧版本(不包括<Application_Home>/Library/Caches子目录).将Documents文件夹用于您可能希望用户有权访问Library的文件,以及该应用程序使用且用户不应看到的文件的文件夹.

另一个更长的方法可能是获取tmp目录的url,首先获取Document目录并剥离最后一个路径组件,然后添加tmp文件夹:

NSURL *documentDir = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] firstObject];
NSURL *tmpDir = [[documentDir URLByDeletingLastPathComponent] URLByAppendingPathComponent:@"tmp" isDirectory:YES];
NSLog(@"tmpDir: %@", [tmpDir path]);

然后我们可以在那里找到一个文件,即pkm.jpg,如下所示:

NSString *fileName = @"pkm";
NSURL *fileURL = [tmpDir URLByAppendingPathComponent:fileName isDirectory:NO];
fileURL = [fileURL URLByAppendingPathExtension:@"jpg"];

使用旧的iOS系统上的字符串可以实现相同的功能,但现在推荐使用上面的第一个URL方法(除非您要写入旧系统:iPhone OS 2或3):

NSString *tmpDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) firstObject];
tmpDir = [[tmpDir stringByDeletingLastPathComponent] stringByAppendingPathComponent:@"tmp"];
NSString *filePath = [[tmpDir stringByAppendingPathComponent:@"pkm"] stringByAppendingPathExtension:@"jpg"];

Answer 2

因为在模拟器中运行的应用程序并不像在 iOS 设备中那样真正沙箱化。在模拟器上，Mac OS 的临时目录在 NSTemporaryDirectory() 中返回 - 在 iOS 设备上，临时目录实际上位于沙箱内。作为应用程序开发人员，您不应担心这种差异。