您似乎正在尝试重新发明轮子伴侣。您可能应该使用 UICollectionView 或 UITableView 而不是 UIScrollView 并手动添加您的单元格。
无论如何，对于你的 scrollView 方法，你可以实现它的一种方式是这样的：
ViewController 头文件
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController
@property (nonatomic, strong) UIScrollView *scrollView;
@property (nonatomic, strong) UIView *contentView;
@end
ViewController 实现文件
#import "ViewController.h"
#import "Cell.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self initViews];
[self initConstraints];
[self fillScrollView:15];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(BOOL)prefersStatusBarHidden
{
return YES;
}
-(void)initViews
{
self.scrollView = [[UIScrollView alloc] init];
// ------------------------------------------------------------------
// This content view will be the only child view of scrollview
// ------------------------------------------------------------------
self.contentView = [[UIView alloc] init];
// add content view to scrollview now
[self.scrollView addSubview:self.contentView];
// add scrollview to main view
[self.view addSubview:self.scrollView];
}
-(void)initConstraints
{
self.scrollView.translatesAutoresizingMaskIntoConstraints = NO;
self.contentView.translatesAutoresizingMaskIntoConstraints = NO;
id views = @{
@"scrollView": self.scrollView,
@"contentView": self.contentView
};
// setup scrollview constraints
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[scrollView]|" options:0 metrics:nil views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[scrollView]|" options:0 metrics:nil views:views]];
// ---------------------------------------
// setup content view constraint
//
// note: need to pin all four side of
// contentView to scrollView
// ---------------------------------------
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[contentView]|" options:0 metrics:nil views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[contentView]|" options:0 metrics:nil views:views]];
}
-(void)fillScrollView:(int) numItems
{
// clear any previous cells before adding new ones
[self.contentView.subviews makeObjectsPerformSelector:@selector(removeFromSuperview)];
// Need to construct the layout visual format string
NSMutableString *strVerticalConstraint = [[NSMutableString alloc] init];
[strVerticalConstraint appendString:@"V:|"];
// this dictionary will hold all the key-value pair that identifies all the subviews
NSMutableDictionary *subviews = [[NSMutableDictionary alloc] init];
for(int i = 0; i < numItems; i++)
{
Cell *cell = [[Cell alloc] init];
// customize the cell's appearance here
cell.leftImage.image = [UIImage imageNamed:@"leftImage.png"];
cell.textLabel.text = @"This is my example text, it could be longer.";
cell.rightImage.image = [UIImage imageNamed:@"rightImage.png"];
[self.contentView addSubview:cell];
cell.translatesAutoresizingMaskIntoConstraints = NO;
id views = @{
@"cell": cell
};
[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[cell]|" options:0 metrics:nil views:views]];
// prevent cell's width to extend beyond screen width
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:cell attribute:NSLayoutAttributeWidth relatedBy:NSLayoutRelationEqual toItem:nil attribute:NSLayoutAttributeWidth multiplier:1.0 constant:self.view.bounds.size.width]];
// cell name
NSString *cellName = [[NSString alloc] initWithFormat:@"cell%d", i];
// construct each cell's vertical constraint to add it strVerticalConstraint
NSString *viewName = nil;
if(i < numItems - 1)
{
viewName = [[NSString alloc] initWithFormat:@"[%@(50)]-10-", cellName];
}
else
{
viewName = [[NSString alloc] initWithFormat:@"[%@(50)]", cellName];
}
[strVerticalConstraint appendString:viewName];
// add cell name to dictionary
[subviews setValue:cell forKey:cellName];
}
[strVerticalConstraint appendString:@"|"];
NSLog(@"strVerticalConstraint: \n%@", strVerticalConstraint);
// Finally, use the long vertical constraint string
[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:strVerticalConstraint options:0 metrics:nil views:subviews]];
}
@end
单元格头文件
#import <UIKit/UIKit.h>
@interface Cell : UIView
@property (nonatomic, strong) UIImageView *leftImage;
@property (nonatomic, strong) UILabel *textLabel;
@property (nonatomic, strong) UIImageView *rightImage;
@end
单元实现文件
#import "Cell.h"
@implementation Cell
-(id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if(self)
{
[self initViews];
[self initConstraints];
}
return self;
}
-(void)initViews
{
self.backgroundColor = [UIColor grayColor];
self.leftImage = [[UIImageView alloc] init];
self.leftImage.contentMode = UIViewContentModeScaleAspectFill;
self.leftImage.clipsToBounds = YES;
self.leftImage.layer.cornerRadius = 10.0;
self.textLabel = [[UILabel alloc] init];
self.textLabel.numberOfLines = 0;
self.textLabel.lineBreakMode = NSLineBreakByWordWrapping;
self.rightImage = [[UIImageView alloc] init];
self.rightImage.contentMode = UIViewContentModeScaleAspectFill;
self.rightImage.layer.cornerRadius = 10.0;
self.rightImage.clipsToBounds = YES;
[self addSubview:self.leftImage];
[self addSubview:self.textLabel];
[self addSubview:self.rightImage];
}
-(void)initConstraints
{
self.leftImage.translatesAutoresizingMaskIntoConstraints = NO;
self.textLabel.translatesAutoresizingMaskIntoConstraints = NO;
self.rightImage.translatesAutoresizingMaskIntoConstraints = NO;
id views = @{
@"leftImage": self.leftImage,
@"textLabel": self.textLabel,
@"rightImage": self.rightImage
};
// horizontal constraints
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-10-[leftImage(20)]-10-[textLabel]-[rightImage(20)]-10-|" options:0 metrics:nil views:views]];
// vertical constraints
[self addConstraint:[NSLayoutConstraint constraintWithItem:self.leftImage attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[self addConstraint:[NSLayoutConstraint constraintWithItem:self.textLabel attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[self addConstraint:[NSLayoutConstraint constraintWithItem:self.rightImage attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[leftImage(20)]" options:0 metrics:nil views:views]];
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[rightImage(20)]" options:0 metrics:nil views:views]];
}
@end
您应该会看到如下内容：
也许您有理由使用滚动视图并手动添加每一行，否则，如果您愿意替代，您可以使用 UICollectionView 或 UITableView。
上面的方法会导致大量的内存使用，你可以想象如果你有 1000 行，应用程序需要计算、渲染和存储 1000 行到内存中。不可扩展，也不可行。
这就是 UITableView 或 UICollectionView 的用武之地，它们会在每个单元格离开屏幕时重用它，您只需要在屏幕上渲染和存储可见单元格。
UICollectionView 演示
所以，如果您想查看 UICollectionView 方法，这是一个演示如何做到这一点：
ViewController 头文件
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController <UICollectionViewDataSource, UICollectionViewDelegate, UICollectionViewDelegateFlowLayout>
@property (nonatomic, strong) UICollectionView *collectionView;
@property (nonatomic, strong) NSArray *items;
@end
ViewController 实现文件
#import "ViewController.h"
#import "CustomCell.h"
@interface ViewController ()
@end
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
[self initViews];
[self initConstraints];
// --------------------------------------------------------
// Hardcoding 15 sample items as the data source.
// Your data might be from a JSON webservice REST API.
// --------------------------------------------------------
self.items = @[
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer.",
@"This is my example text, it could be longer."
];
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
-(void)initViews
{
UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
flowLayout.minimumInteritemSpacing = 0;
flowLayout.minimumLineSpacing = 10;
self.collectionView = [[UICollectionView alloc] initWithFrame:CGRectZero collectionViewLayout:flowLayout];
self.collectionView.backgroundColor = [UIColor whiteColor];
// need to tell CollectionView beforehand the cell class you want to use
[self.collectionView registerClass:[CustomCell class] forCellWithReuseIdentifier:@"cellID"];
self.collectionView.delegate = self;
self.collectionView.dataSource = self;
[self.view addSubview:self.collectionView];
}
-(void)initConstraints
{
self.collectionView.translatesAutoresizingMaskIntoConstraints = NO;
id views = @{
@"collectionView": self.collectionView
};
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[collectionView]|" options:0 metrics:nil views:views]];
[self.view addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[collectionView]|" options:0 metrics:nil views:views]];
}
#pragma mark - UICollectionView Methods -
-(NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return self.items.count;
}
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
// note: reuse identifier must match what you specified in the register cell above
CustomCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"cellID" forIndexPath:indexPath];
// ---------------------------------------------------------------
// hardcoding images here, you might load your images from JSON
// data using an image caching library like SDWebImage
// ---------------------------------------------------------------
cell.leftImage.image = [UIImage imageNamed:@"leftImage.png"];
// getting text data from data source "self.items"
cell.textLabel.text = self.items[indexPath.row];
cell.rightImage.image = [UIImage imageNamed:@"rightImage.png"];
return cell;
}
// ----------------------------------------------------------------
// Tells the collection view the width and height of each cell
// ----------------------------------------------------------------
-(CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
CGSize size = CGSizeMake(self.view.frame.size.width, 50.0);
return size;
}
@end
CustomCell 头文件
#import <UIKit/UIKit.h>
@interface CustomCell : UICollectionViewCell
@property (nonatomic, strong) UIImageView *leftImage;
@property (nonatomic, strong) UILabel *textLabel;
@property (nonatomic, strong) UIImageView *rightImage;
@end
CustomCell 实现文件
#import "CustomCell.h"
@implementation CustomCell
-(id)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if(self)
{
[self initViews];
[self initConstraints];
}
return self;
}
-(void)initViews
{
self.backgroundColor = [UIColor grayColor];
self.leftImage = [[UIImageView alloc] init];
self.leftImage.contentMode = UIViewContentModeScaleAspectFill;
self.leftImage.clipsToBounds = YES;
self.leftImage.layer.cornerRadius = 10.0;
self.textLabel = [[UILabel alloc] init];
self.textLabel.numberOfLines = 0;
self.textLabel.lineBreakMode = NSLineBreakByWordWrapping;
self.rightImage = [[UIImageView alloc] init];
self.rightImage.contentMode = UIViewContentModeScaleAspectFill;
self.rightImage.layer.cornerRadius = 10.0;
self.rightImage.clipsToBounds = YES;
[self.contentView addSubview:self.leftImage];
[self.contentView addSubview:self.textLabel];
[self.contentView addSubview:self.rightImage];
}
-(void)initConstraints
{
self.leftImage.translatesAutoresizingMaskIntoConstraints = NO;
self.textLabel.translatesAutoresizingMaskIntoConstraints = NO;
self.rightImage.translatesAutoresizingMaskIntoConstraints = NO;
id views = @{
@"leftImage": self.leftImage,
@"textLabel": self.textLabel,
@"rightImage": self.rightImage
};
// horizontal constraints
[self addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|-10-[leftImage(20)]-10-[textLabel]-[rightImage(20)]-10-|" options:0 metrics:nil views:views]];
// vertical constraints
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.leftImage attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.contentView attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.textLabel attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.contentView attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[self.contentView addConstraint:[NSLayoutConstraint constraintWithItem:self.rightImage attribute:NSLayoutAttributeCenterY relatedBy:NSLayoutRelationEqual toItem:self.contentView attribute:NSLayoutAttributeCenterY multiplier:1.0 constant:0.0]];
[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[leftImage(20)]" options:0 metrics:nil views:views]];
[self.contentView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:[rightImage(20)]" options:0 metrics:nil views:views]];
}
@end
你最终会得到这样的结果：
看起来一样但效率更高：D
不，我没有上传相同的屏幕截图：P
希望有帮助吗？