警告框扩展应用：给UIAlertView添加UITextField模拟登录框

首先要自定义一个UIAlertView扩展类，如MAlertView：

// MAlertView.h
//
#import <Foundation/Foundation.h>

@interface  MAlertView:UIAlertView {
     UITextField  *passwdField;
     NSInteger  textFieldCount;
}

- (void)addTextField:(UITextField *)aTextField placeHolder:(NSString *)placeHolder;

@end

// MAlertView.m
//
#import "MAlertView.h"

#define kMAlertViewTextFieldHeight  30.0;
#define kMAlertViewMargin  10.0

@implementation MAlertView
- (void)initialize {
}

- (id)initWithTitle:(NSString *)title message:(NSString *)message delegate:(id)delegate cancelButtonTitle:(NSString *)cancelButtonTitle otherButtonTitles:(NSString *)otherButtonTitles,... {
     if((self == [super initWithTitle:title message:message delegate:delegate cancelButtonTitle:cancelButtonTitle otherButtonTitles:otherButttonTitles,nil])) {
     
     }
     return self;
}

- (void)layoutSubviews {
    CGRect rect = self.bounds;
    rect.size.height += textFieldCount*(kMAlertViewTextFieldHeight + kMAlertViewMargin);
    self.bounds = rect;
    float maxLabelY = 0.f;
    int textFieldIndex = 0;
    for (UIView *view in self.subviews) {

        if ([view isKindOfClass:[UIImageView class]]) {
            
        }
       else if ([view isKindOfClass:[UILabel class]]) {
           
            rect = view.frame;
            maxLabelY = rect.origin.y + rect.size.height;
        }
        else if ([view isKindOfClass:[UITextField class]]) {
            
            rect = view.frame;
            rect.size.width = self.bounds.size.width - 2*kMAlertViewMargin;
            rect.size.height = kMAlertViewTextFieldHeight;
            rect.origin.x = kMAlertViewMargin;
            rect.origin.y = maxLabelY + kMAlertViewMargin*(textFieldIndex+1) + kMAlertViewTextFieldHeight*textFieldIndex;
            view.frame = rect;
            textFieldIndex++;
        }
        else {  //UIThreePartButton
            
            rect = view.frame;
            rect.origin.y = self.bounds.size.height - 65.0;
            view.frame = rect;
        }
    }
}

- (void)addTextField:(UITextField *)aTextField placeHolder:(NSString *)placeHolder{
    if (aTextField != nil) {
        textFieldCount++;
        aTextField.frame = CGRectZero;
        aTextField.borderStyle = UITextBorderStyleRoundedRect;
        aTextField.placeholder = placeHolder;
        [self addSubview:aTextField];
        // [self setNeedsLayout];
    }
}

@end

如何使用此扩展类：

MAlertView  *alert = [[MAlertView alloc] initWithTitle:@"Title" message:nil delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"OK",nil];

[alert addTextField:accountField placeHolder:@"Account"];
[alert addTextField:passwdField placeHolder:@"Password"];
[alert show];
[alert release];

效果如图。

进行了简单的封装，只需要用addTextField:placeHolder:方法将textField加进去就好了，其他使用方法和UIAlertView完全一样。
再作些补充说明：因为UIAlertView只有在点击了按钮才能进行交互，所有的text值都是在点击之后获取对应的textField的值。
有些朋友说空值的情况，这个可以在点击之后判断如果是空值就再次弹出alertView就可以了。

以上是通过自定义UIAlertView扩展类来实现UIAlertView模拟登录框的。现在最新的iOS5.0的UIAlertView类控件本身已经可以通过设置属性alertViewStyle来实现了。这一属性可选类型如下：

typedef enum {
    UIAlertViewStyleDefault = 0,
    UIAlertViewStyleSecureTextInput,
    UIAlertViewStylePlainTextInput,
    UIAlertViewStyleLoginAndPasswordInput
}UIAlertViewStyle

本文整理转载自:http://www.cocoachina.com/bbs/read.php?tid=86733