iOS UIPickerView的簡單使用和數組越界問題

一、簡介

UIPickView是在iOS開發者經常用到的一種控件，經常用於城市選擇，日期選擇等。

二、初始化

        UIPickerView * PickerView = [[UIPickerView alloc] initWithFrame:CGRectMake(0, 40, screenW, 260)];
        PickerView.delegate = self;
        PickerView.dataSource = self;
        PickerView.backgroundColor = [UIColor whiteColor];
        [self.view addSubview:PickerView];

三、UIPickView

// 是否顯示指示器，默認爲NO
@property(nonatomic) BOOL showsSelectionIndicator;

// 列數
@property(nonatomic,readonly) NSInteger numberOfComponents;

// 返回某一列有多少行
- (NSInteger)numberOfRowsInComponent:(NSInteger)component;

// 返回某一列的大小
- (CGSize)rowSizeForComponent:(NSInteger)component;

// 某一列某一行的標題控件
- (nullable UIView *)viewForRow:(NSInteger)row forComponent:(NSInteger)component;

// 重新加載所有列（UIPickView）
- (void)reloadAllComponents;

// 重新加載某一列
- (void)reloadComponent:(NSInteger)component;

// 選中到某一列某一行
- (void)selectRow:(NSInteger)row inComponent:(NSInteger)component animated:(BOOL)animated;
// 某一列的行數
- (NSInteger)selectedRowInComponent:(NSInteger)component;

四、UIPickerViewdataSource方法

// 一共有多少組(列)
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView;

// 每列有多少行，傳入的參數component是對應的列
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component;

五、UIPickerViewDelegate

// 列寬
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component;

// 行高
- (CGFloat)pickerView:(UIPickerView *)pickerView rowHeightForComponent:(NSInteger)component;

// 返回字符串類型的文本標題
- (nullable NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;

// 返回字符屬性的字符串類型的文本標題，可改變返回的字符串顏色，但不能改變大小（測試過了）
- (nullable NSAttributedString *)pickerView:(UIPickerView *)pickerView attributedTitleForRow:(NSInteger)row forComponent:(NSInteger)component;

// 返回view類型標題控件
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(nullable UIView *)view;

// 選中
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component;

六、代碼示例-> .m文件，繼承於UIPickView類（兩列）

#import "PickKeyBoardView.h"

@interface PickKeyBoardView () <UIPickerViewDataSource, UIPickerViewDelegate>
@property (nonatomic, retain) NSMutableArray * plarTypeArr;
@property (nonatomic, assign) NSInteger selectRowOfCom1;

@end

@implementation PickKeyBoardView

- (instancetype)init {
    self = [super init];
    if (self) {
        self.dataSource = self;
        self.delegate = self;
        
        _plarTypeArr = [self CityArr];
    }
    return self;
}

- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        self.dataSource = self;
        self.delegate = self;
        
        _plarTypeArr = [self CityArr];
    }
    return self;
}

#pragma mark - UIPickerViewDataSource
// 列數
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
    return 2;
}

// 行數
- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {
    if (component == 0) {
        return self.plarTypeArr.count;
    }
    else {
        NSDictionary * dict = [self.plarTypeArr objectAtIndex:self.selectRowOfCom1];
        NSArray * playArr = [dict objectForKey:@"key2"];
        return playArr.count;
    }
}

// 列寬
- (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component {
    return screenW / 2;
}

// 標題
- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view {
    
    UILabel * label = (UILabel *)view;
    if (label == nil) {
        CGRect frame = CGRectMake(0.0, 0.0, screenW / 2, 40);
        label = [[UILabel alloc] initWithFrame:frame];
        [label setTextAlignment:NSTextAlignmentCenter];
        [label setFont:[UIFont systemFontOfSize:15.0f]];
    }
    
    if (component == 0) {
        label.backgroundColor = [UIColor greenColor];
        NSDictionary * dict = [self.plarTypeArr objectAtIndex:row];
        label.text = [dict valueForKey:@"key1"];
        return label;
    }else {
        label.backgroundColor = [UIColor yellowColor];
        NSDictionary * dict = [self.plarTypeArr objectAtIndex:self.selectRowOfCom1];
        NSArray * playArr = [dict valueForKey:@"key2"];
        label.text = [playArr objectAtIndex:row];
        return label;
    }
}

// 選中
- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {
    
    if (component == 0) {
        self.selectRowOfCom1 = row;
        [pickerView reloadComponent:1];
        [pickerView selectRow:0 inComponent:1 animated:NO];
    }
}

- (NSArray *)CityArr {
    NSArray * array = @[@"福建省",@[@"泉州",@"福州",@"莆田",@"三明",@"廈門"],
                        @"廣東省",@[@"廣州",@"深圳",@"珠海",@"東莞",@"佛山"]];
    
    NSInteger i = 0;
    NSMutableArray * muArr = [[NSMutableArray alloc] init];
    while (i < array.count) {
        NSString * str = [array objectAtIndex:i];
        NSArray * arr = [array objectAtIndex:i+1];
        
        NSDictionary * dict = [[NSDictionary alloc] initWithObjectsAndKeys:str, @"key1", arr, @"key2", nil];
        [muArr addObject:dict];
        
        i = i + 2;
    }
    return muArr;
}

@end