UITextField验证视觉反馈 [英] UITextField Validation visual feedback

问题描述

我有一个uiTextField我正在验证输入，当我输入无效时，有什么方法可以显示输入无效？是否存在显示无效输入状态的内置机制？

i have a uiTextField that i am validating input on, when i have invalid input what are some appropriate ways to show that the input is invalid? is there any built in mechanism for showing invalid input states?

推荐答案

向左侧添加警告图像非常容易UITextField的-hand侧表示该字段需要一个值。

It's pretty easy to add an 'warning' image to the left-hand side of a UITextField to indicate that the field needs a value.

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;
}

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