下拉列表的实现

ComboBoxView.h

 

#import <UIKit/UIKit.h>

@interface ComboBoxView : UIView <UITableViewDelegate, UITableViewDataSource> {
	UILabel			*selectContentLabel;
	UIButton		*pulldownButton;
	UIButton		*hiddenButton;
	UITableView		*comboBoxTableView;
	NSArray			*comboBoxDatasource;
	BOOL			showComboBox;
}

@property (nonatomic, retain) NSArray *comboBoxDatasource;

- (void)initVariables;
- (void)initCompentWithFrame:(CGRect)frame;
- (void)setContent:(NSString *)content;
- (void)show;
- (void)hidden;
- (void)drawListFrameWithFrame:(CGRect)frame withContext:(CGContextRef)context;

@end

 

ComboBoxView.m

 

#import "ComboBoxView.h"

@implementation ComboBoxView

@synthesize comboBoxDatasource;

- (id)initWithFrame:(CGRect)frame {
    if ((self = [super initWithFrame:frame])) {
		[self initVariables];
		[self initCompentWithFrame:frame];
    }
    return self;
}

#pragma mark -
#pragma mark custom methods

- (void)initVariables {
	showComboBox = NO;
}

- (void)initCompentWithFrame:(CGRect)frame {
	selectContentLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 0, frame.size.width - 45, 25)];
	selectContentLabel.font = [UIFont systemFontOfSize:14.0f];
	selectContentLabel.backgroundColor = [UIColor clearColor];
	[self addSubview:selectContentLabel];
	[selectContentLabel release];
	
	pulldownButton = [UIButton buttonWithType:UIButtonTypeCustom];
	[pulldownButton setFrame:CGRectMake(frame.size.width - 25, 0, 25, 25)];
	[pulldownButton setBackgroundImage:[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"down_icon" ofType:@"png"]]
							   forState:UIControlStateNormal];
	[pulldownButton addTarget:self action:@selector(pulldownButtonWasClicked:) forControlEvents:UIControlEventTouchUpInside];
	[self addSubview:pulldownButton];
	
	hiddenButton = [UIButton buttonWithType:UIButtonTypeCustom];
	[hiddenButton setFrame:CGRectMake(0, 0, frame.size.width - 25, 25)];
	hiddenButton.backgroundColor = [UIColor clearColor];
	[hiddenButton addTarget:self action:@selector(pulldownButtonWasClicked:) forControlEvents:UIControlEventTouchUpInside];
	[self addSubview:hiddenButton];
	
	comboBoxTableView = [[UITableView alloc] initWithFrame:CGRectMake(1, 26, frame.size.width -2, frame.size.height - 27)];
	comboBoxTableView.dataSource = self;
	comboBoxTableView.delegate = self;
	comboBoxTableView.backgroundColor = [UIColor clearColor];
	comboBoxTableView.separatorColor = [UIColor blackColor];
	comboBoxTableView.hidden = YES;
	[self addSubview:comboBoxTableView];
	[comboBoxTableView release];
}

- (void)setContent:(NSString *)content {
	selectContentLabel.text = content;
}

- (void)show {
	comboBoxTableView.hidden = NO;
	showComboBox = YES;
	[self setNeedsDisplay];
}

- (void)hidden {
	comboBoxTableView.hidden = YES;
	showComboBox = NO;
	[self setNeedsDisplay];
}

#pragma mark -
#pragma mark custom event methods

- (void)pulldownButtonWasClicked:(id)sender {
	if (showComboBox == YES) {
		[self hidden];
	}else {
		[self show];
	}
}

#pragma mark -
#pragma mark UITableViewDelegate and UITableViewDatasource methods

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
	return [comboBoxDatasource count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
	static NSString *CellIdentifier = @"ListCellIdentifier";
	UITableViewCell *cell = [comboBoxTableView dequeueReusableCellWithIdentifier:CellIdentifier];
	if (cell == nil) {
		cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
	}
	cell.textLabel.text = (NSString *)[comboBoxDatasource objectAtIndex:indexPath.row];
	cell.textLabel.font = [UIFont systemFontOfSize:13.0f];
	cell.accessoryType = UITableViewCellAccessoryNone;
	cell.selectionStyle = UITableViewCellSelectionStyleNone;
	
	return cell;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
	return 25.0f;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
	[self hidden];
	selectContentLabel.text = (NSString *)[comboBoxDatasource objectAtIndex:indexPath.row];
}

- (void)drawListFrameWithFrame:(CGRect)frame withContext:(CGContextRef)context {
	CGContextSetLineWidth(context, 2.0f);
	CGContextSetRGBStrokeColor(context, 0.0f, 0.0f, 0.0f, 1.0f);
	if (showComboBox == YES) {
		CGContextAddRect(context, CGRectMake(0.0f, 0.0f, frame.size.width, frame.size.height));	
	} else {
		CGContextAddRect(context, CGRectMake(0.0f, 0.0f, frame.size.width, 25.0f));
	}
	CGContextDrawPath(context, kCGPathStroke);	
	CGContextMoveToPoint(context, 0.0f, 25.0f);
	CGContextAddLineToPoint(context, frame.size.width, 25.0f);
	CGContextMoveToPoint(context, frame.size.width - 25, 0);
	CGContextAddLineToPoint(context, frame.size.width - 25, 25.0f);
	
	CGContextStrokePath(context);
}

#pragma mark -
#pragma mark drawRect methods

- (void)drawRect:(CGRect)rect {
	[self drawListFrameWithFrame:self.frame withContext:UIGraphicsGetCurrentContext()];
}

#pragma mark -
#pragma mark dealloc memery methods

- (void)dealloc {
	comboBoxTableView.delegate = nil;
	comboBoxTableView.dataSource = nil;
	
	[comboBoxDatasource	release];
	comboBoxDatasource = nil;
	
    [super dealloc];
}

@end

 

效果图：