比较对象的索引

Question

我是 objective C 的新手，我被困在我的任务上。我已经搜索了问题，但 none 似乎回答了我的特定需求，希望你们能提供帮助！ :)

我正在制作一个包含 2 个组件的选择器视图；一个是所有美国，一个是他们的首都。

现在，当按下一个按钮时，我想要一个 'if else statement' 来检查两个数组的索引是否匹配，以及它是否创建了一个动作。有人可以帮我解决开放条件吗？现在它给了我 'expected expression' 错误。

if (_stateList objectAtIndex:[]== _capitalList objectAtIndex[]) {

    // Defining State & capitalnames by row
    NSInteger stateRow = [self.picker selectedRowInComponent:StatesList];
    NSInteger capitalRow = [self.picker selectedRowInComponent:CapitalsList];

    // Defining the Selected states and selected capital in the row
    NSString *selectedState = self.stateList[stateRow];
    NSString *selectedCapital = self.capitalList[capitalRow];

    // Giving a title to the alert message
    NSString *title = [[NSString alloc] initWithFormat:@"You selected %@ and %@", selectedState, selectedCapital];

    // Alert Message
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:@"Thats right, +1 for you!" preferredStyle:UIAlertControllerStyleAlert];

    UIAlertAction *action = [UIAlertAction actionWithTitle:@"Great!" style:UIAlertActionStyleDefault handler:nil];

    [alert addAction:action];
    [self presentViewController:alert animated:YES completion:nil];

    // Updating the scores
    _rightScore++;
    _rightAnswer.text = [NSString stringWithFormat:@"%i", _rightScore];
    _scoreTotal = _rightScore - _wrongScore;
    _scoreLabel.text = [NSString stringWithFormat:@"Score: %i", _scoreTotal];


} else {

    // Defining State & capitalnames by row
    NSInteger stateRow = [self.picker selectedRowInComponent:StatesList];
    NSInteger capitalRow = [self.picker selectedRowInComponent:CapitalsList];

    // Defining the Selected states and selected capital in the row
    NSString *selectedState = self.stateList[stateRow];
    NSString *selectedCapital = self.capitalList[capitalRow];

    // Giving a title to the alert message
    NSString *title = [[NSString alloc] initWithFormat:@"You have selected %@ and %@", selectedState, selectedCapital];

    // Alert Message
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:@"Thats not correct, -1 for you." preferredStyle:UIAlertControllerStyleAlert];

    UIAlertAction *action = [UIAlertAction actionWithTitle:@"Let me try again!" style:UIAlertActionStyleDefault handler:nil];

    [alert addAction:action];
    [self presentViewController:alert animated:YES completion:nil];

    // Updating the scores
    _wrongScore++;
    _wrongAnswer.text = [NSString stringWithFormat:@"%i", _wrongScore];
    _scoreTotal = _rightScore - _wrongScore;
    _scoreLabel.text = [NSString stringWithFormat:@"Score: %i", _scoreTotal];


}

Answer 1

您正在将所选行分配给两个变量 stateRow 和 capitalRow。您似乎想要做的是比较这两个变量以查看它们是否具有相同的值，例如if (stateRow == capitalRow) { ... } else { ... }

HTH

比较对象的索引

Comparing Index At Object

arrays

indexing

objective-c

picker