《精通 iOS 开发》第 07 章学习笔记

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实现日期选取器

日期数据初始化：

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- (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view.
  NSDate *now = [NSDate date];
  [self.datePicker setDate:now animated:YES];
}

获取日期选取器的值：

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- (IBAction)buttonPressed:(UIButton *)sender {
  NSDate *selected = [self.datePicker date];
  NSString *message = [[NSString alloc]
      initWithFormat:@"The date and time you selected is: %@", selected];

  UIAlertView *alert =
      [[UIAlertView alloc] initWithTitle:@"Date and Time Selected"
                                 message:message
                                delegate:nil
                       cancelButtonTitle:@"That's so true!"
                       otherButtonTitles:nil];
  [alert show];
}

实现单滚轮选取器

声明遵循的协议：

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@interface BIDSingleComponentPickerViewController
    : UIViewController <UIPickerViewDelegate, UIPickerViewDataSource>

@end

实现数据源和委托：

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#pragma mark -
#pragma mark Picker Data Source Methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
  return 1;
}

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

#pragma mark Picker Delegate Methods
- (NSString *)pickerView:(UIPickerView *)pickerView
             titleForRow:(NSInteger)row
            forComponent:(NSInteger)component {
  return self.characterNames[row];
}

获取选取器的值：

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- (IBAction)buttonPressed:(UIButton *)sender {
  NSInteger row = [self.singlePicker selectedRowInComponent:0];
  NSString *selected = self.characterNames[row];
  NSString *title =
      [[NSString alloc] initWithFormat:@"You selected %@!", selected];
  UIAlertView *alert =
      [[UIAlertView alloc] initWithTitle:title
                                 message:@"Thank you for choosing."
                                delegate:nil
                       cancelButtonTitle:@"You're Welcome"
                       otherButtonTitles:nil];
  [alert show];
}

实现多滚轮选取器

实现数据源和委托：

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#pragma mark -
#pragma mark Picker Data Source Methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
  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];
  }
}

获取选取器的值：

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- (IBAction)buttonPressed:(UIButton *)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];

  UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Thank you for your order" message:message delegate:nil cancelButtonTitle:@"Great!" otherButtonTitles:nil];

  [alert show];
}

实现依赖型多滚轮选取器

获取包数据：

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- (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];
}

实现数据源和委托：

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#pragma mark -
#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];
  }
}

获取选取器的值：

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- (IBAction)buttonPressed:(UIButton *)sender {
  NSInteger stateRow =
      [self.dependentPicker selectedRowInComponent:kStateComponent];
  NSInteger zipRow =
      [self.dependentPicker selectedRowInComponent:kZipComponent];

  NSString *state = self.states[stateRow];
  NSString *zip = self.zips[zipRow];
  NSString *title =
      [[NSString alloc] initWithFormat:@"You selected zip code %@", zip];
  NSString *message =
      [[NSString alloc] initWithFormat:@"%@ is in %@", zip, state];

  UIAlertView *alert = [[UIAlertView alloc] initWithTitle:title
                                                  message:message
                                                 delegate:nil
                                        cancelButtonTitle:@"OK"
                                        otherButtonTitles:nil];
  [alert show];
}

设置每个滚轮组件的宽度：

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- (CGFloat)pickerView:(UIPickerView *)pickerView
    widthForComponent:(NSInteger)component {
  if (component == kZipComponent) {
    return 90;
  } else {
    return 200;
  }
}

实现自定义视图选取器

实现数据源和委托：

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#pragma mark -
#pragma mark Picker Data Source Methods
- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
  return 5;
}

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

#pragma mark Picker Delegate Methods
- (UIView *)pickerView:(UIPickerView *)pickerView
            viewForRow:(NSInteger)row
          forComponent:(NSInteger)component
           reusingView:(UIView *)view {
  UIImage *image = self.images[row];
  UIImageView *imageView = [[UIImageView alloc] initWithImage:image];
  return imageView;
}

获取选取器的值：

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- (IBAction)spin:(UIButton *)sender {
  BOOL win = NO;
  int numInRow = 1;
  int lastVal = -1;

  for (int i = 0; i < 5; i++) {
    int newValue = random() % [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:.5];
  } else {
    [self performSelector:@selector(showButton) withObject:nil afterDelay:.5];
  }

  self.button.hidden = YES;
  self.winLabel.text = @"";
}

设置每个滚轮组件内容的高度：

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- (CGFloat)pickerView:(UIPickerView *)pickerView
rowHeightForComponent:(NSInteger)component {
  return 70;
}

播放音乐文件：

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- (void)playWinSound {
  if (winSoundID == 0) {
    NSURL *soundURL =
        [[NSBundle mainBundle] URLForResource:@"win" withExtension:@"wav"];

    AudioServicesCreateSystemSoundID((__bridge CFURLRef)soundURL, &winSoundID);
  }

  AudioServicesPlaySystemSound(winSoundID);
  self.winLabel.text = @"WINNING!";
  [self performSelector:@selector(showButton) withObject:nil afterDelay:1.5];
}