iphone - 使用 NSArray 填充 UIActionSheet 按钮

Question

我试图拉出一个 UIActionSheet 来显示当前登录到 Twitter 设置的所有帐户。我获取了所有匹配类型 Twitter 的帐户的 NSArray，然后运行此代码:

UIActionSheet *chooseaccount = [[UIActionSheet alloc]initWithTitle:@"Choose Account" delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles: nil];
for (int i = 0; i < [arrayOfAccounts count]--; i++) {
    [chooseaccount addButtonWithTitle:[arrayOfAccounts objectAtIndex:i]];
}
[chooseaccount addButtonWithTitle:@"Cancel"];
chooseaccount.cancelButtonIndex = arrayOfAccounts.count;
chooseaccount showInView:self.tabBarController.view];

但是，我收到错误消息“不允许分配给‘readonly’返回的 objective-c 消息结果”

对于让 UIActionSheet 显示 Twitter 帐户的所有用户名有什么建议吗？

更新:
经过几条建议后，我将代码更改为:

-(void)twitteraccess {
    ACAccountStore *account = [[ACAccountStore alloc] init];
    ACAccountType *accountType = [account accountTypeWithAccountTypeIdentifier:
                                  ACAccountTypeIdentifierTwitter];

    [account requestAccessToAccountsWithType:accountType options:nil
                                  completion:^(BOOL granted, NSError *error)
    {
        if (granted == YES)
        {
            NSLog(@"Granted");

            NSArray *arrayOfAccounts = [account
                                        accountsWithAccountType:accountType];
            if ([arrayOfAccounts count] > 0)
            {
                NSLog(@"%i", [arrayOfAccounts count]);

                if ([arrayOfAccounts count] > 1) {
                    NSLog(@"Greaterthan1");
                    UIActionSheet *chooseaccount = [[UIActionSheet alloc]initWithTitle:@"Choose Account" delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles: nil];
                    for (int i = 0; i < [arrayOfAccounts count]; i++) {

                        ACAccount * account = [arrayOfAccounts objectAtIndex:i];
                        [chooseaccount addButtonWithTitle:account.username];
                        NSLog(@"%@", account.username);
                    }

                    [chooseaccount addButtonWithTitle:@"Cancel"];
                    chooseaccount.cancelButtonIndex = arrayOfAccounts.count;

                    [chooseaccount showInView:self.tabBarController.view];
                }
                else {

                }

            }
        }
        else {
            if(error.code == 6){
                [self performSelectorOnMainThread:@selector(alertmessagetwitter)
                                       withObject:nil
                                    waitUntilDone:YES];                }
        }
    }];
}

操作表确实会出现，但需要大约 25 秒才能出现。

Answer 1

你不能写[arrayOfAccounts count]--，这实际上扩展为:

[arrayOfAccounts count] = [arrayOfAccounts count] - 1; // assigning to readonly

相反，只需使用 [arrayOfAccounts count] - 1(或快速枚举)。

for (int i = 0; i < [arrayOfAccounts count]-1; i++) { //...

关于 InvalidArgumentException 的编辑:

假设 arrayOfAccounts 包含 ACAccount 对象而不是 NSString:

for (int i = 0; i < [arrayOfAccounts count]-1; i++) { //...
    ACAccount * account = [arrayOfAccounts objectAtIndex:i];
    [chooseaccount addButtonWithTitle:[account userName]];
}