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
1 // 2 // Flag.h 3 // CountriesSelection 4 // 5 // Created by hellovoidworld on 14/12/16. 6 // Copyright (c) 2014年 hellovoidworld. All rights reserved. 7 // 8 9 #import <Foundation/Foundation.h> 10 11 @interface Flag : NSObject 12 13 /** 国家名 */ 14 @property(nonatomic, copy) NSString *name; 15 16 /** 国旗 */ 17 @property(nonatomic, copy) NSString *icon; 18 19 - (instancetype) initWithDictionary:(NSDictionary *) dictionary; 20 + (instancetype) flagWithDictionary:(NSDictionary *) dictionary; 21 22 @end
1 //
2 // Flag.m
3 // CountriesSelection
4 //
5 // Created by hellovoidworld on 14/12/16.
6 // Copyright (c) 2014年 hellovoidworld. All rights reserved.
7 //
8
9 #import "Flag.h"
10
11 @implementation Flag
12
13 - (instancetype) initWithDictionary:(NSDictionary *) dictionary {
14 if (self = [super init]) {
15 [self setValuesForKeysWithDictionary:dictionary];
16 }
17
18 return self;
19 }
20
21 + (instancetype) flagWithDictionary:(NSDictionary *) dictionary {
22 return [[self alloc] initWithDictionary:dictionary];
23 }
24
25 @end
2.拖入PickerView, 准备主界面
3.实现dataSource和delegate方法
1 #pragma mark - dataSource function
2 - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
3 return 1;
4 }
5
6 - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
7 return self.countries.count;
8 }
9
10 #pragma mark - delegate function
11 // 使用返回UIView的row数据返回方法
12 - (UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
13 //todo 创建自定义的view
14 }
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
1 // 2 // FlagView.h 3 // CountriesSelection 4 // 5 // Created by hellovoidworld on 14/12/16. 6 // Copyright (c) 2014年 hellovoidworld. All rights reserved. 7 // 8 9 #import <UIKit/UIKit.h> 10 11 @class Flag; 12 @interface FlagView : UIView 13 14 /** 国旗数据成员 */ 15 @property(nonatomic, strong) Flag *flag; 16 17 /** 自定义构造方法 */ 18 + (instancetype) flagViewWithPickerView:(UIPickerView *) pickerView; 19 20 /** 定义自己的高度 */ 21 + (CGFloat) flagViewHeight; 22 23 @end
1 //
2 // FlagView.m
3 // CountriesSelection
4 //
5 // Created by hellovoidworld on 14/12/16.
6 // Copyright (c) 2014年 hellovoidworld. All rights reserved.
7 //
8
9 #import "FlagView.h"
10 #import "Flag.h"
11
12 @interface FlagView()
13
14 /** 国家名控件 */
15 @property (weak, nonatomic) IBOutlet UILabel *contryLabel;
16 /** 国旗控件 */
17 @property (weak, nonatomic) IBOutlet UIImageView *flagImage;
18
19 @end
20
21 @implementation FlagView
22
23 + (instancetype) flagViewWithPickerView:(UIPickerView *) pickerView {
24 return [[NSBundle mainBundle] loadNibNamed:@"FlagView" owner:nil options:nil].lastObject;
25 }
26
27 /** 加载数据 */
28 - (void) setFlag:(Flag *)flag {
29 _flag = flag;
30
31 // 1.国家名
32 self.contryLabel.text = flag.name;
33
34 // 2.国旗
35 self.flagImage.image = [UIImage imageNamed:flag.icon];
36 }
37
38 /** 定义自己的高度 */
39 + (CGFloat) flagViewHeight {
40 return 44;
41 }
42
43 @end
7.在控制器中加载解析数据
1 //
2 // ViewController.m
3 // CountriesSelection
4 //
5 // Created by hellovoidworld on 14/12/16.
6 // Copyright (c) 2014年 hellovoidworld. All rights reserved.
7 //
8
9 #import "ViewController.h"
10 #import "Flag.h"
11 #import "FlagView.h"
12
13 @interface ViewController () <UIPickerViewDataSource, UIPickerViewDelegate>
14
15 /** 国家选择器 */
16 @property (weak, nonatomic) IBOutlet UIPickerView *pickerView;
17
18 /** 国家数组 */
19 @property(nonatomic, strong) NSArray *countries;
20
21
22 @end
23
24 @implementation ViewController
25
26 - (void)viewDidLoad {
27 [super viewDidLoad];
28 // Do any additional setup after loading the view, typically from a nib.
29
30 // 设置dataSource
31 self.pickerView.dataSource = self;
32 // 设置delegate
33 self.pickerView.delegate = self;
34 }
35
36 - (void)didReceiveMemoryWarning {
37 [super didReceiveMemoryWarning];
38 // Dispose of any resources that can be recreated.
39 }
40
41 /** 加载数据 */
42 - (NSArray *) countries {
43 if (nil == _countries) {
44 NSArray * dictArray = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"flags.plist" ofType:nil]];
45
46 NSMutableArray *mCountriesArray = [NSMutableArray array];
47 for (NSDictionary *dict in dictArray) {
48 Flag *flag = [Flag flagWithDictionary:dict];
49 [mCountriesArray addObject:flag];
50 }
51
52 _countries = mCountriesArray;
53 }
54
55 return _countries;
56 }
57
58 #pragma mark - dataSource function
59 - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
60 return 1;
61 }
62
63 - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
64 return self.countries.count;
65 }
66
67 #pragma mark - delegate function
68 // 使用返回UIView的row数据返回方法
69 - (UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
70 FlagView *flagView = [FlagView flagViewWithPickerView:self.pickerView];
71 flagView.flag = self.countries[row];
72
73 return flagView;
74 }
75
76 /** 设置row的高度 */
77 - (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component {
78 return [FlagView flagViewHeight];
79 }
80
81 @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
1 #pragma mark - delegate function
2 // 使用返回UIView的row数据返回方法
3 - (UIView *) pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
4
5 FlagView *flagView;
6 if (nil == view) {
7 flagView = [FlagView flagViewWithPickerView:self.pickerView];
8 } else {
9 NSLog(@"重用");
10 flagView = (FlagView *)view;
11 }
12
13 flagView.flag = self.countries[row];
14
15 NSLog(@"flagView - %p, view - %p", flagView, view);
16
17 return flagView;
18 }
==》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