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？

#import "ViewController.h"

    @interface ViewController () <UITableViewDatasource,UITableViewDelegate>

    @property(strong,nonatomiC) UITableView *tableView;
    @property(strong,nonatomiC) NSMutableArray *dataArray;
    @property (strong,nonatomiC) UITableViewCell *customcatell;

    @end

    @implementation ViewController

    - (void)viewDidLoad {
        [super viewDidLoad];
        // Do any additional setup after loading the view,typically from a nib.
        self.tableView = [[UITableView alloc] initWithFrame:CGRectMake(0,self.view.frame.size.width,self.view.frame.size.height) style:UITableViewStylePlain];
        [self.tableView setDatasource:self];
        [self.tableView setDelegate:self];
        [self.tableView setShowsVerticalScrollInDicator:NO];
        self.tableView.translatesAutoresizingMaskIntoConsTraints = NO;
        self.tableView.rowHeight = UITableViewAutomaticDimension;
        [self.view addSubview:self.tableView];

        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];


    }

    - (void)didReceiveMemoryWarning {
        [super didReceiveMemoryWarning];
        // Dispose of any resources that can be recreated.
    }

    - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {

        return [self.dataArray count];
    }

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowATindexPath:(NSIndexPath *)indexPath {
        NSString *cellIdentifier = @"Customcatell";
        UITableViewCell *cell = (UITableViewCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];

        if (cell == nil)
        {
            cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reusEIDentifier:cellIdentifier];
        }

        cell.BACkgroundColor = [UIColor colorWithRed:249.0/255 green:237.0/255 blue:224.0/255 alpha:1.0];

        int dataIndex = (int) indexPath.row % [self.dataArray count];
        cell.textLabel.text = self.dataArraY[dataIndex];
        cell.textLabel.numberOfLines = 0;
        cell.textLabel.lineBreakmode = NSLineBreakByWordWrapping;

        NSDictionary *views = @{@"label":cell.textLabel};
        NSArray *consTraints = [NSLayoutConsTraint consTraintsWithVisualFormat:@"H:|[label]|"
                                                                       options:0
                                                                       metrics:nil
                                                                         views:views];
        [cell.contentView addConsTraints:consTraints];

        consTraints = [NSLayoutConsTraint consTraintsWithVisualFormat:@"V:|[label]|"
                                                              options: 0
                                                              metrics:nil
                                                                views:views];
        [cell.contentView addConsTraints:consTraints];

        return cell;

    }

    - (CGFloat)tableView:(UITableView *)tableView heightForRowATindexPath:(NSIndexPath *)indexPath {
        // Calculate a height based on a cell
        if(!self.customcatell) {
            self.customcatell = [self.tableView dequeueReusableCellWithIdentifier:@"Customcatell"];
        }

        // Configure the cell
        int dataIndex = (int) indexPath.row % [self.dataArray count];
        self.customcatell.textLabel.text = self.dataArraY[dataIndex];

        // auto layout

        NSDictionary *views = @{@"label":self.customcatell.textLabel};
        NSArray *consTraints = [NSLayoutConsTraint consTraintsWithVisualFormat:@"H:|[label]|"
                                                                       options:0
                                                                       metrics:nil
                                                                         views:views];
        [self.customcatell.contentView addConsTraints:consTraints];

        consTraints = [NSLayoutConsTraint consTraintsWithVisualFormat:@"V:|[label]|"
                                                              options: 0
                                                              metrics:nil
                                                                views:views];
        [self.customcatell.contentView addConsTraints:consTraints];

        // Layout the cell

        [self.customcatell layoutIfNeeded];

        // Get the height for the cell

        CGFloat height = [self.customcatell.contentView systemLayoutSizeFitTingSize:UILayoutFitTingCompressedSize].height;

        // Padding of 1 point (cell separator)
        CGFloat separatorHeight = 1;

        return height + separatorHeight;
    }

    - (CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowATindexPath:(NSIndexPath *)indexPath {

        return 140;

    }


    @end

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,

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

#import <UIKit/UIKit.h>

@interface RJTableViewCell : UITableViewCell

@property (strong,nonatomiC) UILabel *titleLabel;
@property (strong,nonatomiC) UILabel *bodyLabel;

@end

// RJCell.m

#import "RJTableViewCell.h"

@interface RJTableViewCell ()

@property (nonatomic,assign) BOOL didSetupConsTraints;

@end

@implementation RJTableViewCell

- (id)initWithStyle:(UITableViewCellStylE)style reusEIDentifier:(NSString *)reusEIDentifier {
    self = [super initWithStyle:style reusEIDentifier:reusEIDentifier];
    if (self) {
        // Initialization code

        self.titleLabel = [[UILabel alloc] init];
        [self.titleLabel setTranslatesAutoresizingMaskIntoConsTraints:NO];
        [self.titleLabel setLineBreakmode:NSLineBreakByTruncaTingTail];
        [self.titleLabel setnumberOfLines:1];
        [self.titleLabel setTextAlignment:NSTextAlignmentLeft];
        [self.titleLabel setTextColor:[UIColor blackColor]];
        [self.titleLabel setBACkgroundColor:[UIColor clearColor]];
        [self.contentView addSubview:self.titleLabel];

        // Add this label to the button
        self.bodyLabel = [[UILabel alloc] init];
        [self.bodyLabel setTranslatesAutoresizingMaskIntoConsTraints:NO];
        [self.bodyLabel setContentCompressionResistancePriority:UILayoutPriorityrequired forAxis:UILayoutConsTraintAxisVertical];
        [self.bodyLabel setLineBreakmode:NSLineBreakByTruncaTingTail];
        [self.bodyLabel setnumberOfLines:0];
        [self.bodyLabel setTextAlignment:NSTextAlignmentLeft];
        [self.bodyLabel setTextColor:[UIColor darkGrayColor]];
        [self.bodyLabel setBACkgroundColor:[UIColor clearColor]];
        [self.contentView addSubview:self.bodyLabel];
    }

    return self;
}

- (void)updateConsTraints {
    [super updateConsTraints];

    if (self.didSetupConsTraints) return;

    // Get the views Dictionary
    NSDictionary *viewsDictionary =
        @{
            @"titleLabel" : self.titleLabel,@"bodyLabel" : self.bodyLabel
        };

    NSString *format;
    NSArray *consTraintsArray;

    //Create the consTraints using the visual language format
    format = @"V:|-10-[titleLabel]-10-[bodyLabel]-10-|";
    consTraintsArray = [NSLayoutConsTraint consTraintsWithVisualFormat:format options:0 metrics:nil views:viewsDictionary];
    [self.contentView addConsTraints:consTraintsArray];

    format = @"|-10-[titleLabel]-10-|";
    consTraintsArray = [NSLayoutConsTraint consTraintsWithVisualFormat:format options:0 metrics:nil views:viewsDictionary];
    [self.contentView addConsTraints:consTraintsArray];

    format = @"|-10-[bodyLabel]-10-|";
    consTraintsArray = [NSLayoutConsTraint consTraintsWithVisualFormat:format options:0 metrics:nil views:viewsDictionary];
    [self.contentView addConsTraints:consTraintsArray];

    self.didSetupConsTraints = YES;
}

@end

// RJTableViewController.h

#import <UIKit/UIKit.h>

@interface RJTableViewController : UITableViewController

@end

// RJTableViewController.m

#import "RJTableViewController.h"
#import "RJTableViewCell.h"

static NSString *CellIdentifier = @"CellIdentifier";

@interface RJTableViewController ()

@property(strong,nonatomiC) NSMutableArray *titleArray;
@property(strong,nonatomiC) NSMutableArray *bodyArray;

@end

@implementation RJTableViewController

- (id)initWithStyle:(UITableViewStylE)style
{
    self = [super initWithStyle:style];
    if (self) {
        // Custom initialization
        self.title = @"Table View Controller";
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    [self.tableView registerClass:[RJTableViewCell class] forCellReusEIDentifier:CellIdentifier];
    self.titleArray = [[UIFont familyNames] mutableCopy];
    for(int i = 0; i < 100; i++) {
        [self.titleArray addObjectsFromArray:[UIFont familyNames]];
    }
    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];
}

- (void)contentSizeCategoryChanged:(Nsnotification *)notification
{
    [self.tableView reloadData];
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // Return the number of rows in the section.
    return [self.titleArray count];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowATindexPath:(NSIndexPath *)indexPath
{

    RJTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    int dataIndex = (int) indexPath.row % [self.bodyArray count];
    cell.titleLabel.text =  self.titleArraY[indexPath.row];
    cell.bodyLabel.text = self.bodyArraY[dataIndex];

    // Make sure the consTraints have been added to this cell,since it may have just been created from scratch
    [cell setNeedsupdateConsTraints];

    return cell;
}

- (CGFloat)tableView:(UITableView *)tableView heightForRowATindexPath:(NSIndexPath *)indexPath
{

    RJTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    int dataIndex = (int) indexPath.row % [self.bodyArray count];
    cell.titleLabel.text =  self.titleArraY[indexPath.row];
    cell.bodyLabel.text = self.bodyArraY[dataIndex];

    cell.bodyLabel.preferredMaxLayoutWidth = tableView.bounds.size.width - (20.0 * 2.0f);

    [cell setNeedsupdateConsTraints];
    [cell updateConsTraintsIfNeeded];
    [cell.contentView setNeedsLayout];

    [cell.contentView layoutIfNeeded];

    CGFloat height = [cell.contentView systemLayoutSizeFitTingSize:UILayoutFitTingCompressedSize].height;

    return height;
}

- (CGFloat)tableView:(UITableView *)tableView estimatedHeightForRowATindexPath:(NSIndexPath *)indexPath
{
    return 200.0f;
}

@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.