A.需求
1.使用PickerView做出有3列餐点（水果、主菜、饮料）的搭配Demo
2.选择的餐点实时显示在“显示区”
3.提供“随机”按钮，随机选择菜品搭配
B.实现步骤
1.拖入一个PickerView
2.用控制器配置dataSource和delegate
1//遵守UipickerViewDataSource,UIPickerViewDelegate2@interfaceViewController () <UIPickerViewDataSource, UIPickerViewDelegate>34/** 选择器*/5@PRoperty (weak, nonatomic) IBOutlet UIPickerView *pickerView;67@end89@implementationViewController1011- (void)viewDidLoad {12[super viewDidLoad];13//Do any additional setup after loading the view, typically from a nib.1415//设置dataSource16self.pickerView.dataSource =self;17//设置delegage18self.pickerView.delegate=self;19}
3.实现代理方法
1#pragmamark - 代理方法2/** 列数*/3- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {4return3;5}67/** 对应列的行数*/8- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {9return5;10}1112/** 对应列和行的显示内容*/13- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {14return@"内容";15}
4.引入plist文件，读取数据
1/** 加载数据，延迟加载*/2- (NSArray *) foodCategories {3if(nil ==_foodCategories) {4_foodCategories = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"foods.plist"ofType:nil]];5}67return_foodCategories;8}910#pragmamark - dataSource方法11/** 列数*/12- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {13returnself.foodCategories.count;14}1516/** 对应列的行数*/17- (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {18NSArray *foods =self.foodCategories[component];19returnfoods.count;20}212223#pragmamark - delegate方法24/** 对应列和行的显示内容*/25- (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {26NSArray *foods =self.foodCategories[component];27returnfoods[row];28}
5.制作显示区
1/** 水果*/2@property (weak, nonatomic) IBOutlet UILabel *fruitLabel;3/** 主菜*/4@property (weak, nonatomic) IBOutlet UILabel *mainLabel;5/** 饮料*/6@property (weak, nonatomic) IBOutlet UILabel *drinkLabel;
6.响应选择事件
1/** 响应选择餐点事件*/2- (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component {3NSArray *foods =self.foodCategories[component];4NSString *food =foods[row];56switch(component) {7case0:8self.fruitLabel.text =food;9
break;10case1:11self.mainLabel.text =food;12
break;13case2:14self.drinkLabel.text =food;15
break;16default:17
break;18}
7.制作“随机”功能
1/** 随机选择餐点*/2-(IBAction)onRandomClicked {3//循环所有餐点种类4for(inti=0; i<self.foodCategories.count; i++) {5//之前选择的餐点行数6NSInteger originalRow =[self.pickerView selectedRowInComponent:i];78NSInteger row =originalRow;910//此种类内含有的所有餐点11NSArray *foods =self.foodCategories[i];12//如果随机的餐点跟上一次的相同，继续随机13while(row ==originalRow) {14row = arc4random() %foods.count;15}1617//通知pickerView改变选择18[self.pickerView selectRow:row inComponent:i animated:YES];1920//改变显示区21[self pickerView:self.pickerView didSelectRow:row inComponent:i];22}23}