string - 生成一串随机字符 cocoa ？

Question

我知道如何生成随机数，但我真正需要的是一串随机字符。这是我到目前为止所拥有的:

NSString *letters = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ123456789?%$";

    char generated;
    generated = //how do i define this?

    NSLog(@"generated =%c", generated);
    [textField setStringValue:generated];

Answer 1

-(NSString*)generateRandomString:(int)num {
    NSMutableString* string = [NSMutableString stringWithCapacity:num];
    for (int i = 0; i < num; i++) {
        [string appendFormat:@"%C", (unichar)('a' + arc4random_uniform(25))];
    }
    return string;
}

然后对于 5 个字母的字符串，这样调用:

NSString* string = [self generateRandomString:5];