我的 UIAlertView 不会在 if / else 构造中显示

发布于 2024-12-06 14:15:08 字数 579 浏览 1 评论 0原文

我想确保用户在我的应用程序中弹出视图之前在文本字段中输入一些数据。这是我的代码：

    if (nameField.text == NULL || lastNameField.text == NULL) {                                  
    UIAlertView *alertView= [[UIAlertView alloc] initWithTitle:@"Error" message:@"No 
    patient data         specified, please specify name!" delegate:self 
    cancelButtonTitle:@"Okay" otherButtonTitles:nil];
    [alertView show];
        [alertView release];

问题是每次都会调用 else 语句，即使我故意将 textField 留空。

建议？

我也尝试扭转局面，将 else 部分放在 if 语句中，将要求更改为 != NULL，但这也不起作用

原文

I want to make sure that the user enters some data in a textfield before a view pops up in my app. Here is my code:

    if (nameField.text == NULL || lastNameField.text == NULL) {                                  
    UIAlertView *alertView= [[UIAlertView alloc] initWithTitle:@"Error" message:@"No 
    patient data         specified, please specify name!" delegate:self 
    cancelButtonTitle:@"Okay" otherButtonTitles:nil];
    [alertView show];
        [alertView release];

The problem is the else statement is being called every time, even when I deliberately leave the textField blank.

Suggestions?

I also tried to turn it around, putting the else part in the if statement, changing the requirements to != NULL, but that doesn't work either

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一场信仰旅途 2024-12-13 14:15:08

你的问题是检查它是否为NULL。文本字段永远不会为 NULL。 NULL表示不存在。 textField 确实存在，但您真正想要检查的是该字段中是否有文本。方法是 nameField.length > 0 。所以你的代码应该是：

if (nameField.length == 0 || lastNameField.length == 0) {                                  
    UIAlertView *alertView= [[UIAlertView alloc] initWithTitle:@"Error" message:@"No patient data specified, please specify name!" delegate:self 
    cancelButtonTitle:@"Okay" otherButtonTitles:nil];
    [alertView show];
    [alertView release];

Your problem is checking if it is NULL. The textfield will never be NULL. NULL means it doesn't exist. The textField definatly exists, but what you actually want to check is if there is text in the field. The way to do that is nameField.length > 0. So your code should be:

if (nameField.length == 0 || lastNameField.length == 0) {                                  
    UIAlertView *alertView= [[UIAlertView alloc] initWithTitle:@"Error" message:@"No patient data specified, please specify name!" delegate:self 
    cancelButtonTitle:@"Okay" otherButtonTitles:nil];
    [alertView show];
    [alertView release];

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