ios - 如何制作 "required"UITextFields？

Question

我有一个 ViewController，其中包含我的应用程序用户填写并提交(通过点击 UIButton)的一系列 UITextFields(一种表单)。数据发布到外部数据库 (MySQL)，一切都很好。但是，我希望所有 UITextField 都是“必需的”；换句话说，除非所有字段都已填写(包含值)，否则“提交”按钮不应发布数据。有谁知道我会怎么做？请参阅下面的代码。

ViewController.h

-(IBAction)addParty:(id)sender;

@property (strong, nonatomic) IBOutlet UITextField *firstname;
@property (strong, nonatomic) IBOutlet UITextField *lastname;
@property (strong, nonatomic) IBOutlet UITextField *guestphone;
@property (strong, nonatomic) IBOutlet UITextField *guestemail;
@property (strong, nonatomic) IBOutlet UITextField *guestsize;

@end

ViewController.m

- (IBAction)addParty:(id)sender
{


    NSString *strURL = [NSString stringWithFormat:@"guestfirst=%@&guestlast=%@&guestphone=%@&guestemail=%@&guestsize=%@", firstname.text, lastname.text, guestphone.text, guestemail.text, guestsize.text];
    NSLog(@"%@", strURL);


    NSData *postData = [strURL dataUsingEncoding:NSASCIIStringEncoding allowLossyConversion:YES];
    NSString *postLength = [NSString stringWithFormat:@"%d",[postData length]];
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
    [request setURL:[NSURL URLWithString:@"postgl.php"]];
    [request setHTTPMethod:@"POST"];
    [request setValue:postLength forHTTPHeaderField:@"Content-Length"];
    [request setValue:@"application/x-www-form-urlencoded" forHTTPHeaderField:@"Current-Type"];
    [request setHTTPBody:postData];


    NSURLConnection *conn = [[NSURLConnection alloc]initWithRequest:request delegate:self];

    if(conn)
    {
        NSLog(@"Connection Successful");

        [thankyou setHidden:NO];         
    }
    else
    {
         [thankyou setHidden:YES];
        NSLog(@"Connection could not be made");
    }

}

Answer 1

一种解决方案是将文本字段的委托(delegate)设置为 UIViewController。

在委托(delegate)方法中实现以下内容

- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string; 

一旦实现，您应该拥有如下所示的方法:

- (BOOL)enableSubmitButton
{
    for (UITextField *textField in @[self.firstname, self.lastname, self.guestphone, self.guestemail, self.guestsize]) {
        if (textfield.text.length == 0) {
            return NO;
        }
    }
    return YES;
}

然后你应该有一个按钮集的 IBOutlet，你可以在 shouldChangeCharactersInRange 中调用 enableSubmitButton 并将按钮设置为启用，即

@property (nonatomic, weak) IBOutlet UIButton *submitButton;

or could be UIBarButtonItem

@property (nonatomic, weak) IBOutlet UIBarButtonItem *submitButton;

self.submitButton.enabled = [self enableSubmitButton];