ios - 无法在文件夹中写入 nsdata

Question

代码如下:

NSData * imageData = [NSData dataWithContentsOfURL:imageURL];                

 [imageData writeToFile:savedImagePath options:NSDataWritingAtomic error:&error];
                            if(error != nil)
 NSLog(@"write error %@", error);   

错误:

 write error Error Domain=NSCocoaErrorDomain Code=4 "The operation couldn’t be completed. (Cocoa error 4.)" UserInfo=0x8b7b850 {NSUnderlyingError=0x8b7d7c0 "The operation couldn’t be completed. No such file or directory", NSFilePath=/Users/alfa-1/Library/Application Support/iPhone Simulator/6.0/Applications/C24B228A-599E-4249-97A7-17775E8A546B/Library/Caches/ChannelListImages/http:/direct.domain.com/files/icons/1-all-cb.jpg, NSUserStringVariant=Folder}

Answer 1

在将数据写入文件之前。您需要创建文件夹。按照这些步骤

#define APPLICATION_DATA_DIRECTORY @"Application Data"
+ (NSString *)cachesDirectoryPath
// Returns the path to the caches directory.  This is a class method because it's
// used by +applicationStartup.
{
    NSString *      result;
    NSArray *       paths;

    result = nil;
    paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    if ( (paths != nil) && ([paths count] != 0) ) {
        assert([[paths objectAtIndex:0] isKindOfClass:[NSString class]]);
        result = [paths objectAtIndex:0];
    }
    result = [result stringByAppendingPathComponent:APPLICATION_DATA_DIRECTORY];
    if (![[NSFileManager defaultManager] fileExistsAtPath:result]) {
        [[NSFileManager defaultManager] createDirectoryAtPath:result withIntermediateDirectories:YES attributes:nil error:NULL];
    }

    return result;
}

在此之后:#define kPhotosDirectoryName @"ApplicationDocuments"

    NSMutableString *savePath = [NSMutableString string];
    [savePath appendFormat:@"%@/%@",[YOURClass cachesDirectoryPath],kPhotosDirectoryName];

    [savePath appendFormat:@"/%@",YOUR_FILE_NAME];

    if (![[NSFileManager defaultManager] fileExistsAtPath:savePath]) {
        //write the data to file here
    }