[iOS基础控件 - 6.10.2] PickerView 自定义row内容 国家选择Demo

A.需求

1.自定义一个UIView和xib，包含国家名和国旗显示

2.学习row的重用

 

B.实现步骤

1.准备plist文件和国旗图片

 

 

2.创建模型

 //
 //  Flag.h
 //  CountriesSelection
 //
 //  Created by hellovoidworld on 14/12/16.
 //  Copyright (c) 2014年 hellovoidworld. All rights reserved.
 //

 #import <Foundation/Foundation.h>

 @interface Flag : NSObject

 /** 国家名 */
 @property(nonatomic, copy) NSString *name;

 /** 国旗 */
 @property(nonatomic, copy) NSString *icon;

 - (instancetype) initWithDictionary:(NSDictionary *) dictionary;
 + (instancetype) flagWithDictionary:(NSDictionary *) dictionary;

 @end

 

 //
 //  Flag.m
 //  CountriesSelection
 //
 //  Created by hellovoidworld on 14/12/16.
 //  Copyright (c) 2014年 hellovoidworld. All rights reserved.
 //

 #import "Flag.h"

 @implementation Flag

 - (instancetype) initWithDictionary:(NSDictionary *) dictionary {
     if (self = [super init]) {
         [self setValuesForKeysWithDictionary:dictionary];
     }

     return self;
 }

 + (instancetype) flagWithDictionary:(NSDictionary *) dictionary {
     return [[self alloc] initWithDictionary:dictionary];
 }

 @end

 

2.拖入PickerView, 准备主界面

 

3.实现dataSource和delegate方法

 #pragma mark - dataSource function
 - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
     return ;
 }

 - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
     return self.countries.count;
 }

 #pragma mark - delegate function
 // 使用返回UIView的row数据返回方法
 - (UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
     //todo 创建自定义的view
 }

 

4.创建自定义的UIView

 

5.设计自定row内容的xib，指定class

 

 

 

6.拖入控件到FlagView类，创建初始化方法和加载数据方法

 //
 //  FlagView.h
 //  CountriesSelection
 //
 //  Created by hellovoidworld on 14/12/16.
 //  Copyright (c) 2014年 hellovoidworld. All rights reserved.
 //

 #import <UIKit/UIKit.h>

 @class Flag;
 @interface FlagView : UIView

 /** 国旗数据成员 */
 @property(nonatomic, strong) Flag *flag;

 /** 自定义构造方法 */
 + (instancetype) flagViewWithPickerView:(UIPickerView *) pickerView;

 /** 定义自己的高度 */
 + (CGFloat) flagViewHeight;

 @end

 

 //
 //  FlagView.m
 //  CountriesSelection
 //
 //  Created by hellovoidworld on 14/12/16.
 //  Copyright (c) 2014年 hellovoidworld. All rights reserved.
 //

 #import "FlagView.h"
 #import "Flag.h"

 @interface FlagView()

 /** 国家名控件 */
 @property (weak, nonatomic) IBOutlet UILabel *contryLabel;
 /** 国旗控件 */
 @property (weak, nonatomic) IBOutlet UIImageView *flagImage;

 @end

 @implementation FlagView

 + (instancetype) flagViewWithPickerView:(UIPickerView *) pickerView {
     return [[NSBundle mainBundle] loadNibNamed:@"FlagView" owner:nil options:nil].lastObject;
 }

 /** 加载数据 */
 - (void) setFlag:(Flag *)flag {
     _flag = flag;

     // 1.国家名
     self.contryLabel.text = flag.name;

     // 2.国旗
     self.flagImage.image = [UIImage imageNamed:flag.icon];
 }

 /** 定义自己的高度 */
 + (CGFloat) flagViewHeight {
     return ;
 }

 @end

 

7.在控制器中加载解析数据

 //
 //  ViewController.m
 //  CountriesSelection
 //
 //  Created by hellovoidworld on 14/12/16.
 //  Copyright (c) 2014年 hellovoidworld. All rights reserved.
 //

 #import "ViewController.h"
 #import "Flag.h"
 #import "FlagView.h"

 @interface ViewController () <UIPickerViewDataSource, UIPickerViewDelegate>

 /** 国家选择器 */
 @property (weak, nonatomic) IBOutlet UIPickerView *pickerView;

 /** 国家数组 */
 @property(nonatomic, strong) NSArray *countries;

 @end

 @implementation ViewController

 - (void)viewDidLoad {
     [super viewDidLoad];
     // Do any additional setup after loading the view, typically from a nib.

     // 设置dataSource
     self.pickerView.dataSource = self;
     // 设置delegate
     self.pickerView.delegate = self;
 }

 - (void)didReceiveMemoryWarning {
     [super didReceiveMemoryWarning];
     // Dispose of any resources that can be recreated.
 }

 /** 加载数据 */
 - (NSArray *) countries {
     if (nil == _countries) {
         NSArray * dictArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"flags.plist" ofType:nil]];

         NSMutableArray *mCountriesArray = [NSMutableArray array];
         for (NSDictionary *dict in dictArray) {
             Flag *flag = [Flag flagWithDictionary:dict];
             [mCountriesArray addObject:flag];
         }

         _countries = mCountriesArray;
     }

     return _countries;
 }

 #pragma mark - dataSource function
 - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
     return ;
 }

 - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
     return self.countries.count;
 }

 #pragma mark - delegate function
 // 使用返回UIView的row数据返回方法
 - (UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
     FlagView *flagView = [FlagView flagViewWithPickerView:self.pickerView];
     flagView.flag = self.countries[row];

     return flagView;
 }

 /** 设置row的高度 */
 - (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component {
     return [FlagView flagViewHeight];
 }

 @end

 

out:

 

 

C.row的重用

PickerView没有像TableView一样提供缓存池的方法 dequeueReusableCellWithIdentifier

在PickerView的delegate的row数据加载方法中提供了reusingView，是iOS内核缓存的UIView

 #pragma mark - delegate function
 // 使用返回UIView的row数据返回方法
 - (UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {

     FlagView *flagView;
     if (nil == view) {
         flagView = [FlagView flagViewWithPickerView:self.pickerView];
     } else {
         NSLog(@"重用");
         flagView = (FlagView *)view;
     }

     flagView.flag = self.countries[row];

     NSLog(@"flagView - %p, view - %p", flagView, view);

     return flagView;
 }

 

==》但是在我的操作中，系统由始至终都没有传入缓存的UIView，每次都是使用了代码创建的FlagView

 

out：

2014-12-16 17:02:58.927 CountriesSelection[19352:1505008] flagView - 0x7ba7ee40, view - 0x0
2014-12-16 17:02:58.931 CountriesSelection[19352:1505008] flagView - 0x7b942300, view - 0x0
2014-12-16 17:02:58.936 CountriesSelection[19352:1505008] flagView - 0x79e44b80, view - 0x0
2014-12-16 17:02:58.937 CountriesSelection[19352:1505008] flagView - 0x79f64bc0, view - 0x0
2014-12-16 17:02:58.940 CountriesSelection[19352:1505008] flagView - 0x79f68e00, view - 0x0
2014-12-16 17:02:58.941 CountriesSelection[19352:1505008] flagView - 0x79f6a720, view - 0x0
2014-12-16 17:02:58.942 CountriesSelection[19352:1505008] flagView - 0x79f6bff0, view - 0x0
2014-12-16 17:02:58.943 CountriesSelection[19352:1505008] flagView - 0x79f6ff30, view - 0x0
2014-12-16 17:02:58.944 CountriesSelection[19352:1505008] flagView - 0x79f6e370, view - 0x0
2014-12-16 17:03:00.134 CountriesSelection[19352:1505008] flagView - 0x7b94a6c0, view - 0x0
2014-12-16 17:03:00.168 CountriesSelection[19352:1505008] flagView - 0x7b94b810, view - 0x0
2014-12-16 17:03:00.605 CountriesSelection[19352:1505008] flagView - 0x79f364c0, view - 0x0
2014-12-16 17:03:00.655 CountriesSelection[19352:1505008] flagView - 0x79f439e0, view - 0x0
2014-12-16 17:03:00.657 CountriesSelection[19352:1505008] flagView - 0x79f5a450, view - 0x0
2014-12-16 17:03:00.873 CountriesSelection[19352:1505008] flagView - 0x79f6cc60, view - 0x0

2014-12-16 17:03:01.477 CountriesSelection[19352:1505008] flagView - 0x7b94ce90, view - 0x0