Obj-C 委托在单独的文件中实现

Question

我正在尝试清理我的代码。我的 ViewController 中有 3 个 pickerView，我想在单独的文件中实现委托。

id imp = [[HourPickerImplementation alloc] init];
self.hourPicker.dataSource = imp;
self.hourPicker.delegate = imp;

HourPickerImplementation.h:

@interface HourPickerImplementation : NSObject <UIPickerViewDataSource, UIPickerViewDelegate>

@end

HourPickerImplementation.m:

@implementation HourPickerImplementation {
  NSMutableArray *_pickerData;
}

- (id)init {
  _pickerData = [[NSMutableArray alloc] initWithCapacity:25];
  for (int i = 0; i < 25; i++) {
    [_pickerData addObject:[NSString stringWithFormat:@"%d H.", i]];
  }
  return self;
}

- (NSInteger)numberOfComponentsInPickerView:(UIPickerView *)pickerView {
  return 1;
}

- (NSInteger)pickerView:(UIPickerView *)pickerView
numberOfRowsInComponent:(NSInteger)component {
  return _pickerData.count;
}

- (UIView *)pickerView:(UIPickerView *)pickerView
            viewForRow:(NSInteger)row
          forComponent:(NSInteger)component
           reusingView:(UIView *)view {
  UIImage *img = [UIImage imageNamed:@"icon_lock.png"];
  UIImageView *temp = [[UIImageView alloc] initWithImage:img];
  temp.frame = CGRectMake(51, 20, 20, 20);

  UILabel *channelLabel =
      [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 50, 60)];
  channelLabel.text =
      [NSString stringWithFormat:@"%@", [_pickerData objectAtIndex:row]];
  channelLabel.textColor = [UIColor whiteColor];
  channelLabel.backgroundColor = [UIColor clearColor];

  UIView *tmpView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 110, 60)];
  [tmpView insertSubview:temp atIndex:0];
  [tmpView insertSubview:channelLabel atIndex:1];

  return tmpView;
}

不幸的是，它给了我这个错误：

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x170099c80 V:[UIImageView:0x12751a110(55)]>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.
2015-08-26 10:30:30.489 bollywood[675:103276] Unable to simultaneously satisfy constraints.
    Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. (Note: If you're seeing NSAutoresizingMaskLayoutConstraints that you don't understand, refer to the documentation for the UIView property translatesAutoresizingMaskIntoConstraints) 
(
    "<NSLayoutConstraint:0x17009a540 V:[UIImageView:0x12751c480(55)]>",
    "<NSLayoutConstraint:0x17009a590 V:[UIImageView:0x12751c5c0(50)]>",
    "<NSLayoutConstraint:0x17009a810 V:[UIImageView:0x12751c480]-(12)-[UIImageView:0x12751c5c0]>",
    "<NSLayoutConstraint:0x17009a900 UITableViewCellContentView:0x12751bcd0.bottomMargin == UIImageView:0x12751c5c0.bottom>",
    "<NSLayoutConstraint:0x17009aa40 UIImageView:0x12751c480.top == UITableViewCellContentView:0x12751bcd0.topMargin + 12>",
    "<NSLayoutConstraint:0x1740961c0 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x12751bcd0(139)]>"
)

Will attempt to recover by breaking constraint 
<NSLayoutConstraint:0x17009a540 V:[UIImageView:0x12751c480(55)]>

Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger.
The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKit/UIView.h> may also be helpful.

我做错了什么？它在一个文件中工作，但看起来很糟糕。

Answer 1

该错误暗示您的单元格中的约束无法满足，因为它们中的一组要求布局无法实现。

查看输出，下一行可能是问题所在：

<NSLayoutConstraint:0x1740961c0 'UIView-Encapsulated-Layout-Height' V:[UITableViewCellContentView:0x12751bcd0(139)]>

此限制条件可能是由选择器视图根据您从 rowForHeightForComponent return 获取的内容生成的。这个身高好像是139pts

首先检查您的委托方法是否实际被调用。你说你拆分了文件。猜测是系统将其设置为 139，因为它在移动后没有看到您的新委托代码。

您的其他约束似乎是 2 个高度为 55 和 50 的图像，间隔为 12，顶部边距为 12。约束中的总固定高度为 117。我注意到您也在使用布局来保证边距。如果这不是您想要的，请将其更改为与实际顶部相对。

所以你的问题是单元格内容想要按固定 sizes/spacings 打包，但是当它设置为 139pts 时仍然不能与顶部和底部对齐。

我的建议是检查您计算的行高 return。

您可以通过更改底部图像和内容视图底部对齐的底部约束来解决约束问题，将图像底部从底部固定 >=0内容视图。通过使这个固定 >=0 约束将不再失败。你会看到底部有一个空隙，你现在可以用它来处理你在代码中 return 的高度之间的不匹配。

Answer 2

解法：

问题出在这里：

- (void)viewDidLoad {
  [super viewDidLoad];

  id imp = [[HourPickerImplementation alloc] init];
  self.hourPicker.dataSource = imp;
  self.hourPicker.delegate = imp;
}

完成该方法后，我的委托被解除分配。我不得不将局部变量更改为全局变量。

- (void)viewDidLoad {
  [super viewDidLoad];

  _imp = [[HourPickerImplementation alloc] init];
  self.hourPicker.dataSource = _imp;
  self.hourPicker.delegate = _imp;
}

现在可以使用了（感谢@Rory McKinnel）

Obj-C 委托在单独的文件中实现

Obj-C Delegate implementation in separate file

ios

objective-c

delegates

uipickerview

code-cleanup