iPhone开发之UIActionSheet

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>{

}

@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];

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;
        }
    }
}

- (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;
        }
    }
}

代码样例请下载：http://download.csdn.net/detail/flyter/4274695

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];
}

- (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];
}

- (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];
}

- (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;
        }
    }
}

- (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

#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

#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];
}

-(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：