[iOS基础控件

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 1;
}

- (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 44;
}

@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 1;
}

- (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