UIControl继承自UIView，有
addTarget:action:forControlEvents:方法来触发事件。
UIControl *myView = [[UIControl alloc]
initWithFrame:CGRectMake(10, 15, 160, 80)
];
[myView addTarget:self
action:@selector(changeLable:)
forControlEvents:UIControlEventTouchUpInside];//每一个view都会触发这个事件
-(void)changeLable:(id)sender{
for (UIControl *control in recvAddressCellArray) {
//如果view的个数不唯一，那么我们需要把它放在一个
NSMutableArray中，这里就是recvAddressCellArray
UIView *vi = (UIView*)control;//将UIControl类型强制转化为UIView类型，为了是让我们找到subviews上的控件
NSArray *sup = vi.subviews;//把subviews上的控件放在数组中
for (UILabel *lab in sup) {
[lab setTextColor:UIColorFromRGB(0x373737)];
}
}
}
一定要记住，每一次重新加载的地方要[recvAddressCellArray
removeAllObjects
];

UINavigationItem *item = [navigationBar.items objectAtIndex:0];
UINavigationItem *back = [[UINavigationItem alloc] initWithTitle:@”返回”];
NSArray *items = [[NSArray alloc] initWithObjects:back,item,nil];
[navigationBar setItems:items]; navigationBar.delegate=self;
使用到UINavigationBar的delegate:
- (BOOL)navigationBar:(UINavigationBar *)navigationBar
shouldPopItem:(UINavigationItem *)item{
[self goBack:nil];
return FALSE;
}

//

//  PromptView.h

//  TabBarTest

//

//  Created by kimziv on 7/29/11.

//  Copyright 2011 __MyCompanyName__. All rights reserved.

//

#import <Foundation/Foundation.h>

@protocol PromptViewDelegate;

@interface PromptView : NSObject<UIActionSheetDelegate> {
UIActionSheet    *_promptView;
id<PromptViewDelegate>  _delegate;
}
@property(nonatomic,assign)id<PromptViewDelegate> delegate;

+ (PromptView *)sharedPromptView;
+ (void)setSharedDelegate:(id<PromptViewDelegate>)delegate;
- (void)showPromptView:(NSString *)promptText;
- (void)dismissPromptView;

@end

@protocol PromptViewDelegate <NSObject>

@optional
-(void)cancelButtonDidClicked:(id)sender;

@end

//

//  PromptView.m

//  TabBarTest

//

//  Created by kimziv on 7/29/11.

//  Copyright 2011 __MyCompanyName__. All rights reserved.

//

#import “PromptView.h”
#import “SynthesizeSingleton.h”

@implementation PromptView
@synthesize delegate=_delegate;
SYNTHESIZE_SINGLETON_FOR_CLASS(PromptView);

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

#pragma mark PromptView

- (void)createStatusView{
CGRect frame = CGRectMake(280, 10, 16, 16);
UIActivityIndicatorView* progressInd = [[UIActivityIndicatorView alloc] initWithFrame:frame];
[progressInd startAnimating];
progressInd.activityIndicatorViewStyle = UIActivityIndicatorViewStyleWhiteLarge;

_promptView = [[UIActionSheet alloc] initWithTitle:@”Connecting…” delegate:self cancelButtonTitle:nil destructiveButtonTitle:nil otherButtonTitles:nil];
_promptView.actionSheetStyle = UIActionSheetStyleBlackTranslucent;
[_promptView addSubview:progressInd];

[progressInd release];

UIButton *cancelBtn=[UIButton buttonWithType:UIButtonTypeRoundedRect];
cancelBtn.frame=CGRectMake(30, 10, 40, 20);
//UIButton *cancelBtn=[[UIButton alloc] initWithFrame:CGRectMake(20, 10, 50, 30)];
cancelBtn.titleLabel.font=[UIFont systemFontOfSize:12];
[cancelBtn setTitle:@"取消" forState:UIControlStateNormal];
//[cancelBtn setBackgroundImage:[UIImage imageNamed:<#(NSString *)#>] forState:UIControlStateNormal];
cancelBtn.backgroundColor=[UIColor clearColor];
cancelBtn.alpha=0.5;
[cancelBtn addTarget:self action:@selector(cancelSend:) forControlEvents:UIControlEventTouchUpInside];
[_promptView addSubview:cancelBtn];
//[cancelBtn release];
}
-(IBAction)cancelSend:(id)sender{
[self dismissPromptView];
if ([_delegate respondsToSelector:@selector(cancelButtonDidClicked:)]) {
[_delegate cancelButtonDidClicked:sender];
}
}

- (void)showPromptView:(NSString *)statusText{
if(!_promptView)
{
[self createStatusView];
}

if(![_promptView superview])
[_promptView showInView:[[[[UIApplication sharedApplication] keyWindow] subviews] objectAtIndex:0]];

[_promptView setTitle:statusText];
}

- (void)dismissPromptView{
if([_promptView superview])
[_promptView dismissWithClickedButtonIndex:0 animated:YES];
if(_promptView)
{
[_promptView release];
_promptView = nil;
}
}

#pragma mark – UIActionSheetDelegate

- (void)actionSheet:(UIActionSheet *)actionSheet clickedButtonAtIndex:(NSInteger)buttonIndex
{

}

+(void)setSharedDelegate:(id<PromptViewDelegate>)delegate{
[self sharedPromptView].delegate=delegate;
}

@end

//

//  SynthesizeSingleton.h

//  TabBarTest

//

//  Created by kimziv on 7/29/11.

//  Copyright 2011 __MyCompanyName__. All rights reserved.

//

#define SYNTHESIZE_SINGLETON_FOR_CLASS(classname)

static classname *shared##classname = nil;

+ (classname *)shared##classname

{

@synchronized(self)

{

if (shared##classname == nil)

{

shared##classname = [[self alloc] init];

}

}

return shared##classname;

}

+ (id)allocWithZone:(NSZone *)zone

{

@synchronized(self)

{

if (shared##classname == nil)

{

shared##classname = [super allocWithZone:zone];

return shared##classname;

}

}

return nil;

}

- (id)copyWithZone:(NSZone *)zone

{

return self;

}

- (id)retain

{

return self;

}

- (NSUInteger)retainCount

{

return NSUIntegerMax;

}

- (void)release

{

}

- (id)autorelease

{

return self;

}

• UIPlaceHolderTextView.h

#import <Foundation/Foundation.h>

@interface UIPlaceHolderTextView : UITextView {
    NSString *placeholder;
    UIColor *placeholderColor;

@private
    UILabel *placeHolderLabel;
}

@property (nonatomic, retain) UILabel *placeHolderLabel;
@property (nonatomic, retain) NSString *placeholder;
@property (nonatomic, retain) UIColor *placeholderColor;

-(void)textChanged:(NSNotification*)notification;

@end


UIPlaceHolderTextView.m
#import "UIPlaceHolderTextView.h"

@implementation UIPlaceHolderTextView

@synthesize placeHolderLabel;
@synthesize placeholder;
@synthesize placeholderColor;

- (void)dealloc
{
    [[NSNotificationCenter defaultCenter] removeObserver:self];
    [placeHolderLabel release]; placeHolderLabel = nil;
    [placeholderColor release]; placeholderColor = nil;
    [placeholder release]; placeholder = nil;
    [super dealloc];
}

- (void)awakeFromNib
{
    [super awakeFromNib];
    [self setPlaceholder:@""];
    [self setPlaceholderColor:[UIColor lightGrayColor]];
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
}

- (id)initWithFrame:(CGRect)frame
{
    if( (self = [super initWithFrame:frame]) )
    {
        [self setPlaceholder:@""];
        [self setPlaceholderColor:[UIColor lightGrayColor]];
        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(textChanged:) name:UITextViewTextDidChangeNotification object:nil];
    }
    return self;
}

- (void)textChanged:(NSNotification *)notification
{
    if([[self placeholder] length] == 0)
    {
        return;
    }

    if([[self text] length] == 0)
    {
        [[self viewWithTag:999] setAlpha:1];
    }
    else
    {
        [[self viewWithTag:999] setAlpha:0];
    }
}

- (void)drawRect:(CGRect)rect
{
    if( [[self placeholder] length] > 0 )
    {
        if ( placeHolderLabel == nil )
        {
            placeHolderLabel = [[UILabel alloc] initWithFrame:CGRectMake(8,8,self.bounds.size.width - 16,0)];
            placeHolderLabel.lineBreakMode = UILineBreakModeWordWrap;
            placeHolderLabel.numberOfLines = 0;
            placeHolderLabel.font = self.font;
            placeHolderLabel.backgroundColor = [UIColor clearColor];
            placeHolderLabel.textColor = self.placeholderColor;
            placeHolderLabel.alpha = 0;
            placeHolderLabel.tag = 999;
            [self addSubview:placeHolderLabel];
        }

        placeHolderLabel.text = self.placeholder;
        [placeHolderLabel sizeToFit];
        [self sendSubviewToBack:placeHolderLabel];
    }

    if( [[self text] length] == 0 && [[self placeholder] length] > 0 )
    {
        [[self viewWithTag:999] setAlpha:1];
    }

    [super drawRect:rect];
}

@end
Reference URL:
http://stackoverflow.com/questions/1328638/placeholder-in-uitextview