Xcode_7 iOS_9 普通选择器 Objective-C (8)

1、SingleViewApplication项目，拖一个pickerView控件、一个label和一个button，并且为pickerView和label定义输出口，为button添加事件触发。

2、viewController.h以及.m的代码如下，这里我们吧属性和事件触发声明都放在了头文件中，并且新建三个属性，我们这里用省份和城市来展现普通选择器，所以这三个属性分别是全部数据、当前省的数据和当前市的数据，因为之后还需要用到数据源的链接，所以还声明了委托协议和数据源协议：

////  ViewController.h//  TestProject////  Created by 侯家奇 on 16/8/17.//  Copyright © 2016年 侯家奇. All rights reserved.//#import <UIKit/UIKit.h>@interface ViewController : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource>@property (nonatomic, strong) NSDictionary *pickerData;  //保存全部数据@property (nonatomic, strong) NSArray *pickerProvincesData;  //当前省的数据@property (nonatomic, strong) NSArray *pickerCitiesData;  //当前市的数据@property (weak, nonatomic) IBOutlet UIPickerView *pickerView;@property (weak, nonatomic) IBOutlet UILabel *label;- (IBAction)onclick:(id)sender;- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component;- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;@end

////  ViewController.m//  TestProject////  Created by 侯家奇 on 16/8/17.//  Copyright © 2016年 侯家奇. All rights reserved.//#import "ViewController.h"@interface ViewController ()@end@implementation ViewController- (void)viewDidLoad {    [super viewDidLoad];    // Do any additional setup after loading the view, typically from a nib.    NSBundle *bundle = [NSBundle mainBundle];    NSString *plistPath = [bundle pathForResource:@"provinces_cities" ofType:@"plist"];    NSDictionary *dict = [[NSDictionary alloc] initWithContentsOfFile:plistPath];    self.pickerData = dict;    self.pickerProvincesData = [self.pickerData allKeys];    NSString *selectedProvince = [self.pickerProvincesData objectAtIndex:0];    self.pickerCitiesData = [self.pickerData objectForKey:selectedProvince];        self.pickerView.dataSource = self;    self.pickerView.delegate = self;}- (void)didReceiveMemoryWarning {    [super didReceiveMemoryWarning];    // Dispose of any resources that can be recreated.}- (IBAction)onclick:(id)sender {    NSInteger row1 = [self.pickerView selectedRowInComponent:0];    NSInteger row2 = [self.pickerView selectedRowInComponent:1];    NSString *selected1 = [self.pickerProvincesData objectAtIndex:row1];    NSString *selected2 = [self.pickerCitiesData objectAtIndex:row2];    NSString *title = [[NSString alloc] initWithFormat:@"%@, %@", selected1, selected2];    self.label.text = title;}- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {    return 2;}- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {    if (component == 0) {        return [self.pickerProvincesData count];    } else {        return [self.pickerCitiesData count];    }}- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {    if (component == 0) {        return [self.pickerProvincesData objectAtIndex:row];    } else {        return [self.pickerCitiesData objectAtIndex:row];    }}- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {    if (component == 0) {        NSString *selectedProvince = [self.pickerProvincesData objectAtIndex:row];        NSArray *array = [self.pickerData objectForKey:selectedProvince];        self.pickerCitiesData = array;        [self.pickerView reloadComponent:1];    }}@end

关于数据源协议和委托协议，这里重写了四个方法，前两个是数据源协议，后两个数委托协议：

numberOfComponentsInPickerView：选择器中拨盘的数目。

pickerView:numberOfRowsInComponent：选择器中某个拨盘的行数。

pickerView:titleForRow:forComponent：为选择器中某个拨盘的行数提供显示数据。

pickerView:didSelectRow:inComponent：选中选择器的某个拨盘中的某行时调用。

4、这里我们需要一个资源文件：provinces_cities.plist可以直接用xcode新建，然后省份定义成array，就可以了，自己添加一些选项，目录结构如下：

关于数据源协议和委托协议的链接，可以通过代码的形式，也可以通过InterfaceBuilder工具，以上的代码中定义了连接

    self.pickerView.dataSource = self;    self.pickerView.delegate = self;

分别拖动即可：