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 ;
}

- (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[];
    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 ;
}

- (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: 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/;
    }else{
        return *pickerWidth/;
    }
}

@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 = ;
    int lastVal = -;
    for (int i = ; i <  ; i++) {
        int newValue = arc4random_uniform((uint)[self.images count]);
        if (newValue == lastVal) {
            numInRow++;
        }else{
            numInRow = ;
        }
        lastVal = newValue;

        [self.picker selectRow:newValue inComponent:i animated:YES];
        [self.picker reloadComponent:i];
        if (numInRow >= ) {
            win = YES;
        }
    }

    if (_crunchSoundID == ) {
        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