如何生成随机文件名（Cocoa/Objective-C）

Question

我希望能够使用我的 FTP 代码上传文件，然后能够使用随机生成的名称上传文件（最好是 7 个字符长，只有大小写字母）

这是我的ftp方法：

ftpManager = [[FTPManager alloc] init];
success = NO;
NSArray* serverData = nil;
FMServer* srv = [FMServer serverWithDestination:[@"IP" stringByAppendingPathComponent:@"/"] username:@"username" password:@"password"];
srv.port = self.portField.intValue;
switch (action) {
    case upload:
        success = [ftpManager uploadFile:fileURL toServer:srv];
        break;
    default;
        break;

如何编辑上传到 ftp 服务器的文件名？

编辑：添加了“fileURL”的位置 代码：

fileURL = [NSURL URLWithString:@"/tmp/tmpscr.png"];
    action = upload;
    [self runAction];

Answer 1

我在 NSArray 上给我们一个类别来随机播放

@interface NSArray (RandomUtils)
-(NSArray *)arrayShuffled
@end


@implementation NSArray (RandomUtils)


-(NSArray *)arrayShuffled
{
    NSUInteger count = [self count];
    NSMutableArray *newArray = [NSMutableArray arrayWithArray:self];
    [self enumerateObjectsUsingBlock:^(id obj, NSUInteger index, BOOL *stop) {
        NSUInteger nElements = count - index;
        NSUInteger n = (arc4random_uniform((u_int32_t)nElements)) + index;
        [newArray exchangeObjectAtIndex:index withObjectAtIndex:n];
    }];
    return newArray;
}
@end

并创建可怕的名称，例如：

NSMutableArray *array = [@[] mutableCopy];

for (char i ='a'; i <='z'; ++i) {
    [array addObject:[NSString stringWithFormat:@"%c", i]];
}

for (char i ='A'; i <='Z'; ++i) {
    [array addObject:[NSString stringWithFormat:@"%c", i]];
}

for (int i = 0; i < 10; ++i) {
    [array addObject:[NSString stringWithFormat:@"%i", i]];
}


NSArray *shuffeldArray = [array arrayShuffled];

NSString* name = [[shuffeldArray subarrayWithRange:NSMakeRange(0, 7)] componentsJoinedByString:@""];

Answer 2

这是我通常使用的：

+ (NSURL*)randomFileURLInDocumentsFolder:(NSString*)folderName pathExtension:(NSString*)extension;{
NSString* folderPath =[NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0] stringByAppendingPathComponent:folderName];
// check if folder exists, else create
if (folderName && ![[NSFileManager defaultManager] fileExistsAtPath:folderPath]) {
    [[NSFileManager defaultManager] createDirectoryAtPath:folderPath withIntermediateDirectories:YES attributes:nil error:nil];
}
NSURL* tmp = [NSURL fileURLWithPath:[folderPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%f%d.%@", [[NSDate date] timeIntervalSinceReferenceDate],arc4random()%1000, extension]]];
int count = 0;
while ([[NSFileManager defaultManager] fileExistsAtPath:[tmp path]]) {
    tmp = [NSURL fileURLWithPath:[folderPath stringByAppendingPathComponent:[NSString stringWithFormat:@"%f%d.%@", [[NSDate date] timeIntervalSinceReferenceDate],arc4random()%1000, extension]]];
    count++;
}

return tmp;

}

Answer 3

我有类似的要求，并在NSString 上给自己写了一个类类别，它返回一个给定长度的随机字符串：

编辑

按照@NoahWitherspoon 的建议更新为使用arc4random_uniform

+ (NSString *)randomStringOfLength:(NSInteger)length {

    char str[length+1];

    for (int i=0; i<length; i++){

        char rand = randomChar();

        str[i]=rand;
    }

    str[length]='\0';

    return [NSString stringWithCString:str encoding:NSUTF8StringEncoding];
}

char randomChar(){

    char randomLower = 'a' + arc4random_uniform(26);
    char randomUpper = 'A' + arc4random_uniform(6);
    char randomNumber = '0' + arc4random_uniform(9);

    int randomVal = arc4random_uniform(100);

    char randomAlpha = (randomVal % 2 == 0) ? randomLower : randomUpper;

    //If you don't want a numeric as part of the string, just
    //return randomAlpha

    return (randomVal % 3 == 0) ? randomNumber : randomAlpha;
}

Answer 4

我用非常简单的方法解决了，我给大家展示一下以供参考：

NSString *letters = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";

-(NSString *) randomStringWithLength: (int) len {

NSMutableString *randomString = [NSMutableString stringWithCapacity: len];

for (int i=0; i<len; i++) {
    [randomString appendFormat: @"%C", [letters characterAtIndex: arc4random_uniform([letters length]) % [letters length]]];     }

return randomString;
}

然后我使用这种方法生成长度为 len 的随机混合

NSString* myString = [self randomStringWithLength:7];

希望对大家有帮助！！！