iPhone - 在 UITextfield 下方显示错误消息的最佳方式是什么

Question

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Answer 1

创建一个包含文本字段、标签和验证 block 的新对象模型。 当textfield退出first responder时，调用block检查是否有效，如果不有效，显示label

类似这样的东西

@protocol ValidationTextFieldDelegate

-(void) validationTextField:(ValidationTextField*)textField didResignWithResult:(BOOL)result;

@end

@interface ValidationTextField : NSObject <UITextFieldDelegate>

@property (nonatomic, strong) UITextField *textField;
@property (nonatomic, strong) UILabel *errorLabel;
@property (copy) void(^validationBlock)(BOOL);
@property (nonatomic, assign) id<ValidationTextFieldDelegate> delegate;

@end

@implementation ValidationTextField

-(void)textFieldDidEndEditing:(UITextField*)textField {
    BOOL result = self.validationBlock();

    self.errorLabel.hidden = result;

    if (self.delegate) {
        [self.delegate validationTextField:self didResignWithResult:result];
    }
}

在你的 Controller 中

-(void) validationTextField:(ValidationTextField*)textField didResignWithResult:(BOOL)result {
    if (!result) {
        int yOffset = textField.errorLabel.bounds.size.height;

        // Update here the frames of your other textfields, adding the yOffset to their frames
    }
}