iphone - UITextField 验证视觉反馈

Question

我有一个 uiTextField，我正在验证输入，当我输入无效时，有哪些适当的方法可以显示输入无效？是否有任何内置机制可以显示无效的输入状态？

Answer 1

将“警告”图像添加到 UITextField 的左侧以指示该字段需要一个值非常容易。

试试这个:

UITextField* field = .... your text field ...

if ( fails_validation ) {
  field.leftViewMode = UITextFieldViewModeAlways;
  UIImageView* imageView = [[UIImageView alloc] initWithFrame:CGRectMake(0, 0, 32, 32)];
  imageView.image = [UIImage imageNamed:@"warning.png"];
  imageView.contentMode = UIViewContentModeScaleAspectFit;
  field.leftView = imageView;
} else {
  field.leftViewMode = UITextFieldViewModeNever;
  field.leftView = nil;
}