iOS开发-分页栏和选取器的使用
一、分页栏
创建一个新的项目，Subclass of的值选中UIViewController，然后在storyboard中删除根视图，在右下方拖出一个Tab Bar Controller
新增分页，只需从右下方拖出一个普通的View Controller，按住鼠标右键从分页栏控制器拖动到新视图控制器上释放，在弹出面板中的Relationship Segue标题下选中view controllers，使用这些分页要给他们创建Cocoa Touch Class 并关联。
设置分页栏底部的标题与图标，如图：
二、选取器
选取器分为Date Picker和Picker View，前者是日期选取器，后者为一般选取器，可以任意定制用途。
（一）下面实现一个功能：点击按钮，弹出一个警告视图显示当前在日期选取器中选定的日期和时间
1）往Date分页上拖出一个Date Picker和一个按钮，并设置约束
2）创建日期选取器的输出接口，选中Date Picker，按住右键拖动到实现文件，创建一个名为datePicker的输出接口，如图：
3）加载此视图时，选取器都会重置为当前的日期和时间的实现代码，在viewDidLoad方法中编写，如图：
4）实现功能的操作方法，选中按钮，按住右键拖动到实现文件下方，创建一个名为buttonPressed的操作方法，并编写代码，如图：
5）实现效果，显示的是格林威治标准时间
（二）自定义的选取器视图的实现，下面记录几个要点，与上面相同的步骤就不说了
1）将控制器实现为数据源和委托，关联dateSource和delegate，如图：
2）在.h文件中添加协议
3）创建一个数组，用于向选取器提供数据，并将其赋给characterNames属性，代码如下：
4）按钮的方法和数据源、委托的方法实现，结合上下图
5）实现效果
(三) 实现多滚轮选取器
1）添加委托与数据源协议，与上面相同。
<UIPickerViewDelegate,UIPickerViewDataSource>
2）定义两个选取器滚轮相应的索引值常量，以及相应的两个数组
3）其他方法的实现跟一个选取器差不多，这里只是多了一个判断使用哪个滚轮，代码如下：
@implementation DoubleComponentPickerViewController - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view. // 初始化滚轮的内容 self.fillingTypes = @[@"Ham", @"Turkey", @"Peanut Butter", @"Tuna Salad", @"Chicken Salad", @"Roast Beef", @"Vegemite"]; self.breadTypes = @[@"White", @"Whole Wheat", @"Rye",@"Sourdough", @"Seven Grain"]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } - (IBAction)buttonPressed:(id)sender { NSInteger fillingRow = [self.doublePicker selectedRowInComponent:kFillingComponent]; NSInteger breadRow = [self.doublePicker selectedRowInComponent:kBreadComponent]; NSString *filling = self.fillingTypes[fillingRow]; NSString *bread = self.breadTypes[breadRow]; NSString *message = [[NSString alloc] initWithFormat:@"Your %@ on %@ bread will be right up.",filling,bread]; UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Thank you for your order" message:message preferredStyle:UIAlertControllerStyleAlert]; UIAlertAction *action = [UIAlertAction actionWithTitle:@"Great!" style:UIAlertActionStyleDefault handler:nil]; [alert addAction:action]; [self presentViewController:alert animated:YES completion:nil]; } #pragma mark Picker Data Soure Methods - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { // 滚轮数目2个 return 2; } - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { if (component == kBreadComponent) { return [self.breadTypes count]; }else{ return [self.fillingTypes count]; } } #pragma mark Picker Delegate Methods - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { if (component == kBreadComponent) { return self.breadTypes[row]; }else{ return self.fillingTypes[row]; } } @end
4）运行效果
（四）实现有依赖关系的选取器，即其中的内容变化会引起另一个中的内容变化
由于步骤大同小异，这里只po代码了。。。
// // DependentComponentPickerViewController.m // Pickers // // Created by Jierism on 16/7/19. // Copyright © 2016年 Jierism. All rights reserved. // #import "DependentComponentPickerViewController.h" #define kStateComponent 0 #define kZipComponent 1 @interface DependentComponentPickerViewController () @property (weak, nonatomic) IBOutlet UIPickerView *dependentPicker; @property (strong,nonatomic) NSDictionary *stateZips; @property (strong,nonatomic) NSArray *states; @property (strong,nonatomic) NSArray *zips; @end @implementation DependentComponentPickerViewController - (void)viewDidLoad { [super viewDidLoad]; // Do any additional setup after loading the view. NSBundle *bundle = [NSBundle mainBundle]; NSURL *plistURL = [bundle URLForResource:@"statedictionary" withExtension:@"plist"]; self.stateZips = [NSDictionary dictionaryWithContentsOfURL:plistURL]; NSArray *allStates = [self.stateZips allKeys]; NSArray *sortedStates = [allStates sortedArrayUsingSelector:@selector(compare:)]; self.states = sortedStates; NSString *selectedState = self.states[0]; self.zips = self.stateZips[selectedState]; } - (void)didReceiveMemoryWarning { [super didReceiveMemoryWarning]; // Dispose of any resources that can be recreated. } - (IBAction)buttonPressed:(id)sender { NSInteger stateRow = [self.dependentPicker selectedRowInComponent:kStateComponent]; NSInteger zipRow = [self.dependentPicker selectedRowInComponent:kZipComponent]; NSString *state = self.states[stateRow]; NSString *zip = self.states[zipRow]; NSString *title = [[NSString alloc] initWithFormat:@"You selected zip code %@.",zip]; NSString *message = [[NSString alloc] initWithFormat:@"%@ is in %@",zip,state]; UIAlertController *alert = [UIAlertController alertControllerWithTitle:title message:message preferredStyle:UIAlertControllerStyleAlert]; UIAlertAction *action = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil]; [alert addAction:action]; [self presentViewController:alert animated:YES completion:nil]; } #pragma mark Picker Data Source Methods - (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView { return 2; } - (NSInteger)pickerView:(UIPickerView *)pickerView numberOfRowsInComponent:(NSInteger)component { if (component == kStateComponent) { return [self.states count]; }else{ return [self.zips count]; } } #pragma mark Picker Delegate Methods - (NSString *)pickerView:(UIPickerView *)pickerView titleForRow:(NSInteger)row forComponent:(NSInteger)component { if (component == kStateComponent) { return self.states[row]; }else{ return self.zips[row]; } } - (void)pickerView:(UIPickerView *)pickerView didSelectRow:(NSInteger)row inComponent:(NSInteger)component { if (component == kStateComponent) { NSString *selectedState = self.states[row]; self.zips = self.stateZips[selectedState]; [self.dependentPicker reloadComponent:kZipComponent]; [self.dependentPicker selectRow:0 inComponent:kZipComponent animated:YES]; } } // 调整选取器占用的宽度 - (CGFloat)pickerView:(UIPickerView *)pickerView widthForComponent:(NSInteger)component { CGFloat pickerWidth = pickerView.bounds.size.width; if (component == kZipComponent) { return pickerWidth/3; }else{ return 2*pickerWidth/3; } } @end
注意这里加入了一个.plist文件，涉及到包的使用。什么是包？
包（bundle ）是一种特定类型的文件夹，其中的内容遵循特定的结构。应用程序和框架都是包，这个调用返回的包对象表示我们的应用程序。
（五）用选取器实现的滚轮小游戏
相同的内容也不说了，详见代码
1）接口的声明，这里还添加了游戏声音
2）往选取器里面加载图片
3）实现点击按钮，选取器开始滚动，并在滚动过程中隐藏按钮
- (void)showButton { self.button.hidden = NO; } - (IBAction)spin:(id)sender { BOOL win = NO; int numInRow = 1; int lastVal = -1; for (int i = 0; i < 5 ; i++) { int newValue = arc4random_uniform((uint)[self.images count]); if (newValue == lastVal) { numInRow++; }else{ numInRow = 1; } lastVal = newValue; [self.picker selectRow:newValue inComponent:i animated:YES]; [self.picker reloadComponent:i]; if (numInRow >= 3) { win = YES; } } if (_crunchSoundID == 0) { NSString *path = [[NSBundle mainBundle] pathForResource:@"crunch" ofType:@"wav"]; NSURL *soundURL = [NSURL fileURLWithPath:path]; AudioServicesCreateSystemSoundID((__bridge CFURLRef)soundURL, &_crunchSoundID); } AudioServicesPlaySystemSound(_crunchSoundID); if (win) { [self performSelector:@selector(playWinSound) withObject:nil afterDelay:0.5]; }else{ [self performSelector:@selector(showButton) withObject:nil afterDelay:0.5]; } // 隐藏按钮 self.button.hidden = YES; self.winLabel.text = @" "; }
4）播放声音的方法，点击按钮和获胜时会被调用，播放相应的音乐
5）数据源协议和委托的方法
6）运行效果
