[iOS基礎控制項，ios基礎控制項

[iOS基礎控制項，ios基礎控制項
A.需求1.使用PickerView做出有3列餐點（水果、主菜、飲料）的搭配Demo2.選擇的餐點即時顯示在“顯示區”3.提供“隨機”按鈕，隨機播放菜品搭配 B.實現步驟1.拖入一個PickerView 1 // 遵守UIPickerViewDataSource,UIPickerViewDelegate 2 @interface ViewController () <UIPickerViewDataSource, UIPickerViewDelegate> 3 4 /** 選取器 */ 5 @property (weak, nonatomic) IBOutlet UIPickerView *pickerView; 6 7 @end 8 9 @implementation ViewController10 11 - (void)viewDidLoad {12 [super viewDidLoad];13 // Do any additional setup after loading the view, typically from a nib.14 15 // 設定dataSource16 self.pickerView.dataSource = self;17 // 設定delegage18 self.pickerView.delegate = self;19 } 3.實現代理方法

 1 #pragma mark - 代理方法 2 /** 列數 */ 3 - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { 4     return 3; 5 } 6  7 /** 對應列的行數 */ 8 - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { 9     return 5;10 }11 12 /** 對應列和行的顯示內容 */13 - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {14     return @"內容";15 }

  1 /** 載入資料，消極式載入 */ 2 - (NSArray *) foodCategories { 3 return self.foodCategories = [NSArray arrayWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"foods.plist" ofType:nil]]; 4 } 5 6 #pragma mark - dataSource方法 7 /** 列數 */ 8 - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { 9 return self.foodCategories.count;10 }11 12 /** 對應列的行數 */13 - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component {14 NSArray *foods = self.foodCategories[component];15 return foods.count;16 }17 18 19 #pragma mark - delegate方法20 /** 對應列和行的顯示內容 */21 - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component {22 NSArray *foods = self.foodCategories[component];23 return foods[row];24 }  1 /** 水果 */2 @property (weak, nonatomic) IBOutlet UILabel *fruitLabel;3 /** 主菜 */4 @property (weak, nonatomic) IBOutlet UILabel *mainLabel;5 /** 飲料 */6 @property (weak, nonatomic) IBOutlet UILabel *drinkLabel; 6.響應選擇事件

 1 /** 響應選擇餐時間點事件 */ 2 - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component { 3     NSArray *foods = self.foodCategories[component]; 4     NSString *food = foods[row]; 5     6     switch (component) { 7         case 0: 8             self.fruitLabel.text = food; 9             break;10         case 1:11             self.mainLabel.text = food;12             break;13         case 2:14             self.drinkLabel.text = food;15             break;16         default:17             break;18     }

  1 /** 隨機播放餐點 */ 2 - (IBAction)onRandomClicked { 3 // 迴圈所有餐點種類 4 for (int i=0; i<self.foodCategories.count; i++) { 5 // 之前選擇的餐點行數 6 NSInteger originalRow = [self.pickerView selectedRowInComponent:i]; 7 8 NSInteger row = originalRow; 9 10 // 此種類內含有的所有餐點11 NSArray *foods = self.foodCategories[i];12 // 如果隨機的餐點跟上一次的相同，繼續隨機13 while (row == originalRow) {14 row = arc4random() % foods.count;15 }16 17 // 通知pickerView改變選擇18 [self.pickerView selectRow:row inComponent:i animated:YES];19 20 // 改變顯示區21 [self pickerView:self.pickerView didSelectRow:row inComponent:i];22 }23 }