ios – 如何使用动态单元格高度和自动布局以编程方式创建非常基本的UITableView？

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请注意：我知道在类似的行上有很多例子.我正在寻找最基本的解决方案,只需要最少的设置.

我试图自己创造一个,我知道我离开了..

  1. #import "ViewController.h"
  2.  
  3.     @interface ViewController () <UITableViewDataSource,UITableViewDelegate>
  4.  
  5.     @property(strong,nonatomic) UITableView *tableView;
  6.     @property(strong,nonatomic) NSMutableArray *dataArray;
  7.     @property (strong,nonatomic) UITableViewCell *customCell;
  8.  
  9.     @end
  10.  
  11.     @implementation ViewController
  12.  
  13.     - (void)viewDidLoad {
  14.         [super viewDidLoad];
  15.         // Do any additional setup after loading the view,typically from a nib.
  16.         self.tableView = [[UITableView alloc] initWithFrame:CGRectMake(0,self.view.frame.size.width,self.view.frame.size.height) style:UITableViewStylePlain];
  17.         [self.tableView setDataSource:self];
  18.         [self.tableView setDelegate:self];
  19.         [self.tableView setShowsVerticalScrollIndicator:NO];
  20.         self.tableView.translatesAutoresizingMaskIntoConstraints = NO;
  21.         self.tableView.rowHeight = UITableViewAutomaticDimension;
  22.         [self.view addSubview:self.tableView];
  23.  
  24.         self.dataArray = [@[@"For the past 33 years,I have looked in the mirror every morning and asked myself: 'If today were the last day of my life,would I want to do what I am about to do today?' And whenever the answer has been 'No' for too many days in a row,I know I need to change something. -Steve Jobs",@"Be a yardstick of quality. Some people aren't used to an environment where excellence is expected. - Steve Jobs",@"Innovation distinguishes between a leader and a follower. -Steve Jobs"] mutableCopy];
  25.  
  26.  
  27.     }
  28.  
  29.     - (void)didReceiveMemoryWarning {
  30.         [super didReceiveMemoryWarning];
  31.         // Dispose of any resources that can be recreated.
  32.     }
  33.  
  34.     - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
  35.  
  36.         return [self.dataArray count];
  37.     }
  38.  
  39.     - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
  40.         NSString *cellIdentifier = @"CustomCell";
  41.         UITableViewCell *cell = (UITableViewCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
  42.  
  43.         if (cell == nil)
  44.         {
  45.             cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
  46.         }
  47.  
  48.         cell.backgroundColor = [UIColor colorWithRed:249.0/255 green:237.0/255 blue:224.0/255 alpha:1.0];
  49.  
  50.         int dataIndex = (int) indexPath.row % [self.dataArray count];
  51.         cell.textLabel.text = self.dataArray[dataIndex];
  52.         cell.textLabel.numberOfLines = 0;
  53.         cell.textLabel.lineBreakMode = NSLineBreakByWordWrapping;
  54.  
  55.         NSDictionary *views = @{@"label":cell.textLabel};
  56.         NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[label]|"
  57.                                                                        options:0
  58.                                                                        metrics:nil
  59.                                                                          views:views];
  60.         [cell.contentView addConstraints:constraints];
  61.  
  62.         constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[label]|"
  63.                                                               options: 0
  64.                                                               metrics:nil
  65.                                                                 views:views];
  66.         [cell.contentView addConstraints:constraints];
  67.  
  68.         return cell;
  69.  
  70.     }
  71.  
  72.     - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath {
  73.         // Calculate a height based on a cell
  74.         if(!self.customCell) {
  75.             self.customCell = [self.tableView dequeueReusableCellWithIdentifier:@"CustomCell"];
  76.         }
  77.  
  78.         // Configure the cell
  79.         int dataIndex = (int) indexPath.row % [self.dataArray count];
  80.         self.customCell.textLabel.text = self.dataArray[dataIndex];
  81.  
  82.         // auto layout
  83.  
  84.         NSDictionary *views = @{@"label":self.customCell.textLabel};
  85.         NSArray *constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"H:|[label]|"
  86.                                                                        options:0
  87.                                                                        metrics:nil
  88.                                                                          views:views];
  89.         [self.customCell.contentView addConstraints:constraints];
  90.  
  91.         constraints = [NSLayoutConstraint constraintsWithVisualFormat:@"V:|[label]|"
  92.                                                               options: 0
  93.                                                               metrics:nil
  94.                                                                 views:views];
  95.         [self.customCell.contentView addConstraints:constraints];
  96.  
  97.         // Layout the cell
  98.  
  99.         [self.customCell layoutIfNeeded];
  100.  
  101.         // Get the height for the cell
  102.  
  103.         CGFloat height = [self.customCell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height;
  104.  
  105.         // Padding of 1 point (cell separator)
  106.         CGFloat separatorHeight = 1;
  107.  
  108.         return height + separatorHeight;
  109.     }
  110.  
  111.     - (CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowAtIndexPath:(NSIndexPath *)indexPath {
  112.  
  113.         return 140;
  114.  
  115.     }
  116.  
  117.  
  118.     @end

解决方法

经过大量的例子,我终于明白了什么是错的.它是其中一个缺少线条会扰乱整个代码的东西之一.对我来说是,
  1. cell.bodyLabel.preferredMaxLayoutWidth = tableView.bounds.size.width;

我们需要在heightForRowAtIndexPath方法中添加它或者它给出约束错误.

我得到了解决方案,感谢其中一个评论的惊人答案here.虽然在答案中给出的示例代码中,上面的代码行在函数cellForRowAtIndexPath而不是heightForRowAtIndexPath中.但我的代码无法以这种方式运行.

所以,基本代码是,

// RJCell.h

  1. #import <UIKit/UIKit.h>
  2.  
  3. @interface RJTableViewCell : UITableViewCell
  4.  
  5. @property (strong,nonatomic) UILabel *titleLabel;
  6. @property (strong,nonatomic) UILabel *bodyLabel;
  7.  
  8. @end

// RJCell.m

  1. #import "RJTableViewCell.h"
  2.  
  3. @interface RJTableViewCell ()
  4.  
  5. @property (nonatomic,assign) BOOL didSetupConstraints;
  6.  
  7. @end
  8.  
  9. @implementation RJTableViewCell
  10.  
  11. - (id)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier {
  12.     self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];
  13.     if (self) {
  14.         // Initialization code
  15.  
  16.         self.titleLabel = [[UILabel alloc] init];
  17.         [self.titleLabel setTranslatesAutoresizingMaskIntoConstraints:NO];
  18.         [self.titleLabel setLineBreakMode:NSLineBreakByTruncatingTail];
  19.         [self.titleLabel setNumberOfLines:1];
  20.         [self.titleLabel setTextAlignment:NSTextAlignmentLeft];
  21.         [self.titleLabel setTextColor:[UIColor blackColor]];
  22.         [self.titleLabel setBackgroundColor:[UIColor clearColor]];
  23.         [self.contentView addSubview:self.titleLabel];
  24.  
  25.         // Add this label to the button
  26.         self.bodyLabel = [[UILabel alloc] init];
  27.         [self.bodyLabel setTranslatesAutoresizingMaskIntoConstraints:NO];
  28.         [self.bodyLabel setContentCompressionResistancePriority:UILayoutPriorityrequired forAxis:UILayoutConstraintAxisVertical];
  29.         [self.bodyLabel setLineBreakMode:NSLineBreakByTruncatingTail];
  30.         [self.bodyLabel setNumberOfLines:0];
  31.         [self.bodyLabel setTextAlignment:NSTextAlignmentLeft];
  32.         [self.bodyLabel setTextColor:[UIColor darkGrayColor]];
  33.         [self.bodyLabel setBackgroundColor:[UIColor clearColor]];
  34.         [self.contentView addSubview:self.bodyLabel];
  35.     }
  36.  
  37.     return self;
  38. }
  39.  
  40. - (void)updateConstraints {
  41.     [super updateConstraints];
  42.  
  43.     if (self.didSetupConstraints) return;
  44.  
  45.     // Get the views dictionary
  46.     NSDictionary *viewsDictionary =
  47.         @{
  48.             @"titleLabel" : self.titleLabel,@"bodyLabel" : self.bodyLabel
  49.         };
  50.  
  51.     NSString *format;
  52.     NSArray *constraintsArray;
  53.  
  54.     //Create the constraints using the visual language format
  55.     format = @"V:|-10-[titleLabel]-10-[bodyLabel]-10-|";
  56.     constraintsArray = [NSLayoutConstraint constraintsWithVisualFormat:format options:0 metrics:nil views:viewsDictionary];
  57.     [self.contentView addConstraints:constraintsArray];
  58.  
  59.     format = @"|-10-[titleLabel]-10-|";
  60.     constraintsArray = [NSLayoutConstraint constraintsWithVisualFormat:format options:0 metrics:nil views:viewsDictionary];
  61.     [self.contentView addConstraints:constraintsArray];
  62.  
  63.     format = @"|-10-[bodyLabel]-10-|";
  64.     constraintsArray = [NSLayoutConstraint constraintsWithVisualFormat:format options:0 metrics:nil views:viewsDictionary];
  65.     [self.contentView addConstraints:constraintsArray];
  66.  
  67.     self.didSetupConstraints = YES;
  68. }
  69.  
  70. @end

// RJTableViewController.h

  1. #import <UIKit/UIKit.h>
  2.  
  3. @interface RJTableViewController : UITableViewController
  4.  
  5. @end

// RJTableViewController.m

  1. #import "RJTableViewController.h"
  2. #import "RJTableViewCell.h"
  3.  
  4. static NSString *CellIdentifier = @"CellIdentifier";
  5.  
  6. @interface RJTableViewController ()
  7.  
  8. @property(strong,nonatomic) NSMutableArray *titleArray;
  9. @property(strong,nonatomic) NSMutableArray *bodyArray;
  10.  
  11. @end
  12.  
  13. @implementation RJTableViewController
  14.  
  15. - (id)initWithStyle:(UITableViewStyle)style
  16. {
  17.     self = [super initWithStyle:style];
  18.     if (self) {
  19.         // Custom initialization
  20.         self.title = @"Table View Controller";
  21.     }
  22.     return self;
  23. }
  24.  
  25. - (void)viewDidLoad
  26. {
  27.     [super viewDidLoad];
  28.  
  29.     [self.tableView registerClass:[RJTableViewCell class] forCellReuseIdentifier:CellIdentifier];
  30.     self.titleArray = [[UIFont familyNames] mutableCopy];
  31.     for(int i = 0; i < 100; i++) {
  32.         [self.titleArray addObjectsFromArray:[UIFont familyNames]];
  33.     }
  34.     self.bodyArray = [@[@"Lorem ipsum dolor sit amet,consectetur adipiscing elit,sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.",@"Ut enim ad minim veniam,quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.Ut enim ad minim veniam,quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.",@"Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.",@"Excepteur sint occaecat cupidatat non proident,sunt in culpa qui officia deserunt mollit anim id est laborum."] mutableCopy];
  35. }
  36.  
  37. - (void)contentSizeCategoryChanged:(NSNotification *)notification
  38. {
  39.     [self.tableView reloadData];
  40. }
  41.  
  42. #pragma mark - Table view data source
  43.  
  44. - (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
  45. {
  46.     // Return the number of sections.
  47.     return 1;
  48. }
  49.  
  50. - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
  51. {
  52.     // Return the number of rows in the section.
  53.     return [self.titleArray count];
  54. }
  55.  
  56. - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
  57. {
  58.  
  59.     RJTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
  60.  
  61.     int dataIndex = (int) indexPath.row % [self.bodyArray count];
  62.     cell.titleLabel.text =  self.titleArray[indexPath.row];
  63.     cell.bodyLabel.text = self.bodyArray[dataIndex];
  64.  
  65.     // Make sure the constraints have been added to this cell,since it may have just been created from scratch
  66.     [cell setNeedsUpdateConstraints];
  67.  
  68.     return cell;
  69. }
  70.  
  71. - (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
  72. {
  73.  
  74.     RJTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
  75.  
  76.     int dataIndex = (int) indexPath.row % [self.bodyArray count];
  77.     cell.titleLabel.text =  self.titleArray[indexPath.row];
  78.     cell.bodyLabel.text = self.bodyArray[dataIndex];
  79.  
  80.     cell.bodyLabel.preferredMaxLayoutWidth = tableView.bounds.size.width - (20.0 * 2.0f);
  81.  
  82.     [cell setNeedsUpdateConstraints];
  83.     [cell updateConstraintsIfNeeded];
  84.     [cell.contentView setNeedsLayout];
  85.  
  86.     [cell.contentView layoutIfNeeded];
  87.  
  88.     CGFloat height = [cell.contentView systemLayoutSizeFittingSize:UILayoutFittingCompressedSize].height;
  89.  
  90.     return height;
  91. }
  92.  
  93. - (CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowAtIndexPath:(NSIndexPath *)indexPath
  94. {
  95.     return 200.0f;
  96. }
  97.  
  98. @end

基本上,棘手的部分是在两个地方,首先设置约束.二,实现方法heightForRowAtIndexPath和cellForRowAtIndexPath.

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