iOS边练边学--UIPickerView和UIDatePicker的简单使用

一、点菜系统练习（UIPickerView）

<1>UIPickerView的常用代理方法介绍

#pragma mark - <UIPickerViewDelegate>

// 返回指定列的行宽度
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component
{
    
}
// 返回指定列中行的高度
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component
{
    
}

// 返回第component列的第row行的字符串
- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    
}
// 富文本属性，可以描述文字的大小和颜色
- (nullable NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    
}
// 返回一个UIView 第component列第row行
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(nullable UIView *)view
{
    
}
// 人为选择第component列第row行之后执行的代码
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    
}

<2>UIPickerView必须实现的两个数据源方法

#pragma mark - <UIPickerViewDataSource>

// 告诉pickView有多少列
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return self.foods.count;
}

// 告诉pickView的component列中有多少行
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return [self.foods[component] count];
}

<3>练习代码

#import "ViewController.h"

@interface ViewController () <UIPickerViewDataSource,UIPickerViewDelegate>
@property (weak, nonatomic) IBOutlet UIPickerView *pickView;
/** 数据集合 */
@property(nonatomic,strong) NSArray *foods;
@property (weak, nonatomic) IBOutlet UILabel *fruitLabel;
@property (weak, nonatomic) IBOutlet UILabel *mainLabel;
@property (weak, nonatomic) IBOutlet UILabel *drinkLabel;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    for (int i = 0; i < self.foods.count; i++) {
        [self pickerView:self.pickView didSelectRow:0 inComponent:i];
    }
    
}
// 随机
- (IBAction)random:(id)sender {
    for (int i = 0; i <self.foods.count; i++) {
        int r = arc4random_uniform((int)[self.foods[i] count]);
        [self.pickView selectRow:r inComponent:i animated:YES];
        [self pickerView:self.pickView didSelectRow:r inComponent:i];
    }
}

// 懒加载数据
- (NSArray *)foods
{
    if (_foods == nil) {
        NSString *path = [[NSBundle mainBundle] pathForResource:@"foods.plist" ofType:nil];
        _foods = [NSArray arrayWithContentsOfFile:path];
    }
    return _foods;
}

#pragma mark - <UIPickerViewDataSource>

// 告诉pickView有多少列
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return self.foods.count;
}

// 告诉pickView的component列中有多少行
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return [self.foods[component] count];
}

#pragma mark - <UIPickerViewDelegate>

// 返回指定列中行的高度
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component
{
    return 60;
}

// 返回第component列的第row行的字符串
- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    return self.foods[component][row];
}

// 人为选择第component列第row行之后执行的代码
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    switch (component) {
        case 0:
            self.fruitLabel.text = self.foods[component][row];
            break;
        case 1:
            self.mainLabel.text = self.foods[component][row];
            break;
        case 2:
            self.drinkLabel.text = self.foods[component][row];
            break;
    }
}

@end

二、国旗选择练习（pickerView每行都是返回一个自定义控件）

//
//  ViewController.m
//  0322国旗选择
//
//  Created by admin on 16/3/22.
//  Copyright © 2016年 admin. All rights reserved.
//

#import "ViewController.h"
#import "ChaosFlag.h"
#import "ChaosFlagView.h"

@interface ViewController () <UIPickerViewDataSource,UIPickerViewDelegate>
/** 数据模型集合 */
@property(nonatomic,strong) NSMutableArray *flags;
@property (weak, nonatomic) IBOutlet UIPickerView *pickView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    _pickView.delegate = self;
    _pickView.dataSource = self;
}
- (NSMutableArray *)flags
{
    if (_flags == nil) {
        NSString *path = [[NSBundle mainBundle] pathForResource:@"flags.plist" ofType:nil];
        NSArray *dicArray = [NSArray arrayWithContentsOfFile:path];
        NSMutableArray *arr = [NSMutableArray array];
        for (NSDictionary *dict in dicArray) {
            ChaosFlag *flag = [ChaosFlag flagWithDict:dict];
            [arr addObject:flag];
        }
        _flags = arr;
    }
    return _flags;
}

#pragma mark - <UIPickerViewDataSource>
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    return self.flags.count;
}

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 1;
}

#pragma mark - 代理方法
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view
{
    // 加载xib
    ChaosFlagView *flagView = [[NSBundle mainBundle] loadNibNamed:@"ChaosFlagView" owner:nil options:nil][0];
    ChaosFlag *flag = self.flags[row];
    flagView.flag = flag;
    return flagView;
}
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component
{
    return 70;
}
@end

三、生日选择，省市二级联动

//
//  ViewController.m
//  0323-生日城市选择器
//
//  Created by admin on 16/3/23.
//  Copyright © 2016年 admin. All rights reserved.
//

#import "ViewController.h"
#import "ChaosProvince.h"

@interface ViewController () <UITextFieldDelegate,UIPickerViewDataSource,UIPickerViewDelegate>
@property (weak, nonatomic) IBOutlet UITextField *birthdayLabel;
@property (weak, nonatomic) IBOutlet UITextField *cityLabel;

/** 数据集合 */
@property(nonatomic,strong) NSMutableArray *provinces;

/** datePicker */
@property(nonatomic,strong) UIDatePicker *datePicker;
/** pickView */
@property(nonatomic,strong) UIPickerView *pickView;
/** 选中的省会索引，用来保存上一次选择的省索引，防止同时拖拽省和市时报错 */
@property(nonatomic,assign) NSInteger proIndex;
@end

@implementation ViewController

// 重写get方法，实现懒加载
- (NSMutableArray *)provinces
{
    if (_provinces == nil) {
        // 初始化数据模型，必须要实例化对象！国旗选择的练习中没有实例化，数据出不来，找了老半天！
        _provinces = [NSMutableArray array];
        NSString *path = [[NSBundle mainBundle] pathForResource:@"provinces.plist" ofType:nil];
        NSArray *dicArray = [NSArray arrayWithContentsOfFile:path];
        for (NSDictionary *dict in dicArray) {
            ChaosProvince *province = [ChaosProvince provinceWithDict:dict];
            [_provinces addObject:province];
        }
    }
    return _provinces;
}

- (void)viewDidLoad {
    [super viewDidLoad];
    
    _cityLabel.delegate = self;
    
    _birthdayLabel.delegate = self;
    [self setBirthdayInputView];
    [self setCitiesInputView];
}
/** 给文本框设置时间选择器的方法 */
- (void)setBirthdayInputView
{
    // 给生日文本框设置datePicker
    _datePicker = [[UIDatePicker alloc] init];
    // 设置时间选择器的语言 zh--中国
    _datePicker.locale = [[NSLocale alloc] initWithLocaleIdentifier:@"zh"];
    // 设置时间选择器显示的时间格式
    _datePicker.datePickerMode = UIDatePickerModeDate;
    _birthdayLabel.inputView = _datePicker;
    // 想要监听一个控件，没有delegate，就找addTarget方法（这个的前提是控件继承自UIControl）
    [_datePicker addTarget:self action:@selector(dateChange:) forControlEvents:UIControlEventValueChanged];
}
/** 监听时间选择器改变的方法 */
- (void)dateChange:(UIDatePicker *)datePicker
{
    // 取出时间
    NSDate *date = datePicker.date;
    // NSDate与NSString之间的转换
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    formatter.dateFormat =@"yyyy-MM-dd";
    NSString *time = [formatter stringFromDate:date];
    _birthdayLabel.text = time;
}

/** 给城市文本框设置选择器的方法 */
- (void)setCitiesInputView
{
    _pickView = [[UIPickerView alloc] init];
    _pickView.delegate = self;
    _pickView.dataSource = self;
    _cityLabel.inputView = _pickView;
}

#pragma mark - pickView数据源方法
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component
{
    if (component == 0) { // 省的个数
        return self.provinces.count;
    } else { // 省对应的城市
        ChaosProvince *province = self.provinces[self.proIndex];
        return province.cities.count;
    }
}

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView
{
    return 2; // 两列
}

#pragma mark - pickerView代理方法
- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component
{
    if (component == 0) { // 省
        ChaosProvince *province = self.provinces[row];
        return province.name;
    }
    else // 城市
    {
        // 根据省的索引获取对应的城市
        ChaosProvince *province = self.provinces[self.proIndex];
        return province.cities[row];
    }
}

// 滚动pickerView就调用
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component
{
    if (component == 0) { // 选择省,刷新相应的城市
        [pickerView reloadComponent:1];
        // 记录当前选中的省会索引
        self.proIndex = [pickerView selectedRowInComponent:0];
    }
    // 显示到文本框中
    
    // 选中的省
    ChaosProvince *province = self.provinces[self.proIndex];
    
    // 选中的城市
    NSInteger cityIndex = [pickerView selectedRowInComponent:1];
    self.cityLabel.text = [NSString stringWithFormat:@"%@ %@",province.name,province.cities[cityIndex]];
    
}

#pragma mark - <UITextFieldDelegate>
// 文本框开始编辑的时候执行的方法
- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    if (textField == self.birthdayLabel) { //生日文本
        
        [self dateChange:_datePicker];
    } else if (textField == self.cityLabel) { // 城市文本
        [self pickerView:self.pickView didSelectRow:0 inComponent:0];
    }
}

// 是否允许在范围内改变字符
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string
{
    return NO;
}
@end