iPhone开发【6】常用控件之Picker View

转载请注明出处，原文网址：http://blog.csdn.net/m_changgong/article/details/8112404 作者：张燕广

实现的功能：演示Picker View的使用方法

关键词：Picker View

1、创建一个Single View Application工程，命名为：PickersDemo，如下图

2、修改ViewController.xib，添加一个Picker View和一个Button控件，如下

连接输出口、操作，如下

3、控制ViewController，需要实现协议UIPickerViewDataSource、UIPickerViewDelegate中的必须实现的方法，

在工程目录依次展开Frameworks->UIKit.framework->Headers，然后打开UIPickerView.h，在文件的尾部可以看到协议UIPickerViewDataSource、UIPickerViewDelegate的定义，如下

4、修改ViewController.h：

////  ViewController.h//  PickersDemo////  Created by Zhang Yanguang on 12-10-25.//  Copyright (c) 2012年 MyCompanyName. All rights reserved.//#import <UIKit/UIKit.h>#define kDeviceCategory 0#define kDeviceName 1@interface ViewController : UIViewController@property(strong,nonatomic)IBOutlet UIPickerView *picker;@property(nonatomic,retain)NSDictionary *appleDevices;@property(nonatomic,retain)NSArray *deviceCategory;@property(nonatomic,retain)NSArray *deviceName;-(IBAction)buttonPressed:(id)sender;@end

5、修改ViewController.m：

////  ViewController.m//  PickersDemo////  Created by Zhang Yanguang on 12-10-25.//  Copyright (c) 2012年 MyCompanyName. All rights reserved.//#import "ViewController.h"@interface ViewController ()@end@implementation ViewController@synthesize picker;@synthesize appleDevices;@synthesize deviceCategory;@synthesize deviceName;- (void)viewDidLoad{    [super viewDidLoad];	// Do any additional setup after loading the view, typically from a nib.    NSArray *array1 = [NSArray arrayWithObjects:@"iPhone",@"iPad",@"iPod",nil];    NSArray *array2 = [NSArray arrayWithObjects:@"Mac",@"iMac",@"Mac Mini",@"Mac Pro",nil];    NSDictionary  *dictionary= [NSDictionary dictionaryWithObjectsAndKeys:array1,@"Mobile",array2,@"Computers",nil];//注意用nil结束    appleDevices = [[NSDictionary alloc]initWithDictionary:dictionary copyItems:YES];        NSArray *components = [self.appleDevices allKeys];    NSArray *sorted = [components sortedArrayUsingSelector:@selector(compare:)];    self.deviceCategory = sorted;        NSString *selectedCategory = [self.deviceCategory objectAtIndex:0];    self.deviceName = [self.appleDevices objectForKey:selectedCategory];}- (void)viewDidUnload{    [super viewDidUnload];    picker = nil;    appleDevices = nil;    deviceCategory = nil;    deviceName = nil;    // Release any retained subviews of the main view.}-(void)dealloc{    [picker release];    [appleDevices release];    [deviceCategory release];    [deviceName release];}-(IBAction)buttonPressed:(id)sender{    NSString *selectedCategory = [self.deviceCategory objectAtIndex:[self.picker selectedRowInComponent:kDeviceCategory]];    NSString *selectedDevice = [self.deviceName objectAtIndex:[self.picker selectedRowInComponent:kDeviceName]];    //NSLog(@"%@-%@",selectedCategory,selectedDevice);    UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"结果" message:[NSString stringWithFormat:@"%@:%@",selectedCategory,selectedDevice]  delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];    [alertView show];}- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation{    return (interfaceOrientation != UIInterfaceOrientationPortraitUpsideDown);}#pragma mark Picker View  DataSource methods// returns the number of 'columns' to display.- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{    return 2;}// returns the # of rows in each component..- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component{    if(component == kDeviceCategory){        return [self.deviceCategory count];    }else{        return [self.deviceName count];    }}#pragma mark Picker View  Delegate methods- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{    if(component == kDeviceCategory){        return [self.deviceCategory objectAtIndex:row];    }else{        return [self.deviceName objectAtIndex:row];    }}- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{    if(component == kDeviceCategory){        NSString *selectedCategory = [self.deviceCategory objectAtIndex:row];        NSArray *array = [self.appleDevices objectForKey:selectedCategory];        self.deviceName = array;                [self.picker selectRow:0 inComponent:kDeviceName animated:YES];        [self.picker reloadComponent:kDeviceName];    }}@end

6、编译、运行，效果如下：

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