【iOS发展-70】点菜系统案例：使用文本框inputView和inputAccessoryView串联UIPickerView、UIDatePicker和UIToolBar

（1）效果

（2）先在storyboard中设计界面，然后源码（直接在ViewController中码）

#import "ViewController.h"

@interface ViewController ()<UIPickerViewDataSource,UIPickerViewDelegate>
@property (nonatomic,strong) NSArray *foods;
@property (weak, nonatomic) IBOutlet UITextField *fruitText;
@property (weak, nonatomic) IBOutlet UITextField *MainfoodText;
@property (weak, nonatomic) IBOutlet UITextField *BeverageText;
@property (strong,nonatomic) UIPickerView *foodPicker;
@property (weak, nonatomic) IBOutlet UITextField *dateText;
@property(strong,nonatomic) UIDatePicker *datePicker;
@end

@implementation ViewController

- (void)viewDidLoad {
    _foodPicker=[[UIPickerView alloc]init];
    _foodPicker.dataSource=self;
    _foodPicker.delegate=self;
    self.fruitText.inputView=_foodPicker;
    self.MainfoodText.inputView=_foodPicker;
    self.BeverageText.inputView=_foodPicker;

    UIToolbar *foodToolBar=[[UIToolbar alloc]init];
    foodToolBar.barTintColor=[UIColor grayColor];
    foodToolBar.frame=CGRectMake(0, 0, 320, 38);
    UIBarButtonItem *randomBtn=[[UIBarButtonItem alloc]initWithTitle:@"随机" style:UIBarButtonItemStylePlain target:self action:@selector(randomPicker)];
    [randomBtn setTintColor:[UIColor whiteColor]];
    UIBarButtonItem *doneBtn=[[UIBarButtonItem alloc]initWithTitle:@"完毕" style:UIBarButtonItemStylePlain target:self action:@selector(doneClick)];
    [doneBtn setTintColor:[UIColor whiteColor]];
    UIBarButtonItem *spaceBtn=[[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemFlexibleSpace target:nil action:nil];
    foodToolBar.items=@[randomBtn,spaceBtn,doneBtn];
    self.fruitText.inputAccessoryView=foodToolBar;
    self.MainfoodText.inputAccessoryView=foodToolBar;
    self.BeverageText.inputAccessoryView=foodToolBar;

    _datePicker=[[UIDatePicker alloc]init];
    _datePicker.datePickerMode=UIDatePickerModeDate;
    _datePicker.locale=[[NSLocale alloc]initWithLocaleIdentifier:@"zh_CN"];
    UIToolbar *dateToolBar=[[UIToolbar alloc]init];
    UIBarButtonItem *doneBtn1=[[UIBarButtonItem alloc]initWithTitle:@"完毕" style:UIBarButtonItemStylePlain target:self action:@selector(dateDoneClick)];
    dateToolBar.barTintColor=[UIColor grayColor];
    dateToolBar.frame=CGRectMake(0, 0, 320, 38);
    dateToolBar.items=@[spaceBtn,doneBtn1];
    self.dateText.inputView=_datePicker;
    self.dateText.inputAccessoryView=dateToolBar;

    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
}

-(void)randomPicker{
    for (int i=0; i<self.foods.count; i++) {
        int row=arc4random()%[self.foods[i] count];
        [self.foodPicker selectRow:row inComponent:i animated:YES];
        [self pickerView:nil didSelectRow:row inComponent:i];
    }
}

-(void)doneClick{
    [self.view endEditing:YES];
    for (int i=0; i<self.foods.count; i++) {
        [self pickerView:nil didSelectRow:[self.foodPicker selectedRowInComponent:i] inComponent:i];
    }
}

-(void)dateDoneClick{
    [self.view endEditing:YES];
    NSDateFormatter *formatter=[[NSDateFormatter alloc]init];
    [formatter setDateFormat:@"YYYY-MM-dd"];
    NSString *newDate=[formatter stringFromDate:self.datePicker.date];
    self.dateText.text=[NSString stringWithFormat:@"%@",newDate];
}

-(NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView{
    return self.foods.count;
}

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

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component{
    return self.foods[component][row];
}

-(void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component{
    if (component==0) {
        self.fruitText.text=self.foods[component][row];
    }else if (component==1){
        self.MainfoodText.text=self.foods[component][row];
    }else{
        self.BeverageText.text=self.foods[component][row];
    }
}

-(NSArray *)foods{
    if (_foods==nil) {
        _foods=[NSArray arrayWithContentsOfFile:[[NSBundle mainBundle]pathForResource:@"foods.plist" ofType:nil]];
    }
    return _foods;
}

@end

（3）总结

——这些选择器，基本都是结合输入框来使用的，即代替原本的键盘。所以我们的设置主要是用到了输入框的inputView属性。

——并且这些弹出的选择器一般上面会有一个UIToolBar，这里用到的是inputAccessoryView属性。

——并且这个UIToolBar里面放得都是UIBarButtonItem元素。我们能够自己定义也能够使用默认的，最重要的是UIBarButtonSystemItemFlexibleSpace用来对齐布局的。

——这里用的UIPickerView仅仅是显示字符串。而有的则须要显示更高级的东西，所以就须要用到view。而不是title。

- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component;

- (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view;

上面假设用到view作为UIPickerView内容，它也被设计成缓冲池回收机构。