[源码下载]UIActionSheet详解

本文源码：http://download.csdn.net/detail/flyter/4274763

UIActionSheet是iOS开发中实现警告框的重要的类，在很多情况下都要用到，先来一睹其芳容：

实现步骤如下：

一、为了让控制器类充当操作表的委托，控制器类需要遵从UIActionSheetDelegate协议。

 @interface UIActionSheetDemoViewController : UIViewController <UIActionSheetDelegate>{

 }

二、生成UIActionSheet并显示。

 UIActionSheet *actionSheet = [[UIActionSheet alloc] initWithTitle:@"Are you sure?"
                                                          delegate:self
                                                 cancelButtonTitle:@"No way!"
                                            destructiveButtonTitle:@"Yes, I'm sure."
                                                 otherButtonTitles:@"Button One", @"Button Two", nil];
 [actionSheet showInView:self.view];
 [actionSheet release];

三、点击按钮后的事件。

 - (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex {
     NSLog(@"%i", buttonIndex);
     if (buttonIndex == actionSheet.cancelButtonIndex) {
         return;
     }
     switch (buttonIndex) {
         case 0: {
             NSLog(@"Item 1 Selected");
             break;
         }
         case 1: {
             NSLog(@"Item 2 Selected");
             break;
         }
         case 2: {
             NSLog(@"Item 3 Selected");
             break;
         }
     }
 }

下面说说如何动态地添加UIActionSheet按钮。

 

一、UIActionSheet的通常实现方法：

 - (void)testActionSheetStatic {
     UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:@"Static UIActionSheet"
                                                        delegate:self
                                               cancelButtonTitle:@"Cancel"
                                          destructiveButtonTitle:nil
                                               otherButtonTitles:@"Item A", @"Item B", @"Item C", nil];
     [sheet showFromRect:view.bounds inView:view animated:YES];
     [sheet release];
 }

 

 

二、 如果事先知道各个按钮并且再也不会改变的情况下，这样的实现是OK的。但如果我要在运行时改变应该怎么办呢？动态添加按钮看起来应该也很简单，不要init函数中指定而在之后添加可以了，如下代码就展示了这点。

 - (void)testActionSheetDynamic {
     // 创建时仅指定取消按钮
     UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:@"Dynamic UIActionSheet"
                                                        delegate:self
                                               cancelButtonTitle:@"Cancel"
                                          destructiveButtonTitle:nil
                                               otherButtonTitles:nil];
     // 逐个添加按钮（比如可以是数组循环）
     [sheet addButtonWithTitle:@"Item A"];
     [sheet addButtonWithTitle:@"Item B"];
     [sheet addButtonWithTitle:@"Item C"];
     [sheet showFromRect:view.bounds inView:view animated:YES];
     [sheet release];
 }

 

        运行下就发现问题很明显——取消按钮是在视图的顶部，而标准做法是显示在底部。怎么解决呢？如果在init函数中添加取消按钮就无法解决了。最后找到了一种将取消按钮也动态添加。

 - (void)testActionSheetDynamic {
     // 创建时不指定按钮
     UIActionSheet *sheet = [[UIActionSheet alloc] initWithTitle:@"Dynamic UIActionSheet"
                                                        delegate:self
                                               cancelButtonTitle:nil
                                          destructiveButtonTitle:nil
                                               otherButtonTitles:nil];
     // 逐个添加按钮（比如可以是数组循环）
     [sheet addButtonWithTitle:@"Item A"];
     [sheet addButtonWithTitle:@"Item B"];
     [sheet addButtonWithTitle:@"Item C"];

     // 同时添加一个取消按钮
     [sheet addButtonWithTitle:@"Cancel"];
     // 将取消按钮的index设置成我们刚添加的那个按钮，这样在delegate中就可以知道是那个按钮
      sheet.cancelButtonIndex = sheet.numberOfButtons-1;
     [sheet showFromRect:view.bounds inView:view animated:YES];
     [sheet release];
 }

 

        这样取消按钮就显示在底部并且行为也符合预期了。

        对我来说现在剩下的最大一个疑问就是destructive按钮到底是什么（Apple文档也没有清晰地说明这点）？一些实验结果也表明它实际上和 取消按钮并无区别，只不过它有一个红色背景而不是黑色的。所有如果在上例中改变destructiveButtonIndex而不是 cancelButtonIndex，就可以看到标有“取消”的按钮有红色背景了。

 

三、出于完整性的考虑，和上述代码相匹配的delegate代码如下：

 - (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
 {
     if (buttonIndex == actionSheet.cancelButtonIndex) {
         return;
     }
     switch (buttonIndex)
     {
         case 0: {
             NSLog(@"Item A Selected");
             break;
         }
         case 1: {
             NSLog(@"Item B Selected");
             break;
         }
         case 2: {
             NSLog(@"Item C Selected");
             break;
         }
     }
 }

 

最后说说如何自定义一个UIActionSheet类。

 

一、自定义CustomActionSheet类。

CustomActionSheet类继承UIActionSheet，具体的实现如下所示：

（1）CustomActionSheet.h头文件：

 #import <UIKit/UIKit.h>

 @interface CustomActionSheet : UIActionSheet {
     UIToolbar* toolBar;
     UIView* view;
 }

 @property(nonatomic,retain)UIView* view;
 @property(nonatomic,retain)UIToolbar* toolBar;

 -(id)initWithHeight:(float)height WithSheetTitle:(NSString*)title;

 @end

（2）CustomActionSheet.m实现文件：

 #import "CustomActionSheet.h"

 @implementation CustomActionSheet

 @synthesize view;
 @synthesize toolBar;

 -(id)initWithHeight:(float)height WithSheetTitle:(NSString*)title{
     self = [super init];
     if (self) {
         int theight = height - 40;
         int btnnum = theight/50;
         for(int i=0; i<btnnum; i++){
             [self addButtonWithTitle:@" "];
         }
         toolBar = [[UIToolbar alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
         toolBar.barStyle = UIBarStyleBlackOpaque;
         UIBarButtonItem *titleButton = [[UIBarButtonItem alloc] initWithTitle:title
                                                                         style:UIBarButtonItemStylePlain
                                                                        target:nil
                                                                        action:nil];

         UIBarButtonItem *rightButton = [[UIBarButtonItem alloc] initWithTitle:@"Done"
                                                                         style:UIBarButtonItemStyleDone
                                                                        target:self
                                                                        action:@selector(done)];

         UIBarButtonItem *leftButton  = [[UIBarButtonItem alloc] initWithTitle:@"Cancel"
                                                                         style:UIBarButtonItemStyleBordered
                                                                        target:self
                                                                        action:@selector(docancel)];

         UIBarButtonItem *fixedButton  =
             [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace
                                                           target:nil
                                                           action:nil];

         NSArray *array =
             [[NSArray alloc] initWithObjects:leftButton,fixedButton,titleButton,fixedButton,rightButton,nil];
         [toolBar setItems: array];
         [titleButton release];
         [leftButton release];
         [rightButton release];
         [fixedButton release];
         [array release];
         [self addSubview:toolBar];
         view = [[UIView alloc] initWithFrame:CGRectMake(0, 44, 320, height-44)];
         view.backgroundColor = [UIColor groupTableViewBackgroundColor];
         [self addSubview:view];
     }
     return self;
 }

 -(void)done{
     [self dismissWithClickedButtonIndex:0 animated:YES];
 }

 -(void)docancel{
     [self dismissWithClickedButtonIndex:0 animated:YES];
 }

 -(void)dealloc{
     [view release];
     [super dealloc];
 }

 @end

二、利用自定义的CustomActionSheet类显示提示框。

 -(IBAction)doClick:(id)sender{
     CustomActionSheet* sheet = [[CustomActionSheet alloc] initWithHeight:284.0f
                                                           WithSheetTitle:@"自定义ActionSheet"];
     UILabel* label = [[UILabel alloc] initWithFrame:CGRectMake(0,50, 320, 50)];
     label.text = @"这里是要自定义放的控制";
     label.backgroundColor = [UIColor clearColor];
     label.textAlignment = UITextAlignmentCenter;
     [sheet.view addSubview:label];

     [sheet showInView:self.view];
     [sheet release];
 }

演示：

 

代码样例请下载：http://download.csdn.net/detail/flyter/4274763