https://github.com/550872569/PictureChoice.git
代码可直接复制使用;
示意图:

iOS-OC图片选择器.gif

AppDelegate

#import "AppDelegate.h"
#import "YHPPictureChoiceController.h"
@interface AppDelegate ()
@end
@implementation AppDelegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  self.window = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
    self.window.rootViewController = [[YHPPictureChoiceController alloc]init];
    [self.window makeKeyAndVisible];
    return YES;
}
@end


YHPPictrueChoicesFlowLayout
#import "YHPPictrueChoicesFlowLayout.h"
@implementation YHPPictrueChoicesFlowLayout
/** 在 collectionView 第一次布局的时候调用，此时 collectionView 的 frame 已经设置完毕 */
- (void)prepareLayout {
    // 一定 super
    [super prepareLayout];
    /** item大小 */
    CGFloat H = (kSCREEN_WIDTH - 2*10 - 3*10) / 4;
    CGFloat W = H;
    self.itemSize = CGSizeMake(W, H);
    /** 列间距 */
    self.minimumInteritemSpacing = 10;
    /** 行间距 */
    self.minimumLineSpacing = 10;
    /** 滚动方向 */
    self.scrollDirection = UICollectionViewScrollDirectionVertical;
    /** 弹簧效果 */
    self.collectionView.bounces = NO;
    /** 分页 */
    self.collectionView.pagingEnabled = YES;
    /** 水平滚动指示条 */
    self.collectionView.showsHorizontalScrollIndicator = NO;
    /** 垂直滚动指示条 */
    self.collectionView.showsVerticalScrollIndicator = NO;
}
@end


YHPPictureChoiceCell

#import <UIKit/UIKit.h>
/** 代理 */
@class YHPPictureChoiceCell;
/** 代理协议 */
@protocol YHPPictureChoiceCellDelegate <NSObject>
/** 代理方法 */
- (void)addPicture:(YHPPictureChoiceCell *)cell;
- (void)removePicture:(YHPPictureChoiceCell *)cell;
@end
@interface YHPPictureChoiceCell : UICollectionViewCell
/** 添加图片按钮 */
@property (nonatomic, strong) UIButton *addBtn;
/** 删除图片按钮 */
@property (nonatomic, strong) UIButton *removeBtn;
/** 图片 */
@property (nonatomic, strong) UIImage *picture;
@property (nonatomic, strong) NSIndexPath * indexpath;
/** 代理属性 */
@property (nonatomic, assign) id <YHPPictureChoiceCellDelegate> delegate;
@end
#import "YHPPictureChoiceCell.h"
@interface YHPPictureChoiceCell ()
@end
@implementation YHPPictureChoiceCell
- (void)setPicture:(UIImage *)picture {
    _picture = picture;
}
#pragma mark - 懒加载属性
/** 添加图片按钮 */
-(UIButton *)addBtn {
    if (!_addBtn) {
        _addBtn = [[UIButton alloc]init];
        [self addSubview:_addBtn];
        _addBtn.frame = self.bounds;
    }
    return _addBtn;
}
/** 删除图片按钮 */
-(UIButton *)removeBtn {
    if (!_removeBtn) {
        _removeBtn = [[UIButton alloc]init];
        [self addSubview:_removeBtn];
        _removeBtn.frame = CGRectMake(self.bounds.size.width*0.75, 0, self.bounds.size.width * 0.25, self.bounds.size.width * 0.25);
        [_removeBtn setImage:[UIImage imageNamed:@"compose_photo_close"] forState:UIControlStateNormal];
    }
    return _removeBtn;
}
/** collectionViewCell 的 frame 是根据之前的 layout 已经确定好的！*/
- (instancetype)initWithFrame:(CGRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        /** 添加子控件 */
        [self setupUI];
    }
    return self;
}
/** 添加子控件 */
- (void)setupUI {
    /** 添加图片按钮 */
    [self.addBtn addTarget:self action:@selector(add) forControlEvents:UIControlEventTouchUpInside];
    /** 删除图片按钮 */
      [self.removeBtn addTarget:self action:@selector(remove) forControlEvents:UIControlEventTouchUpInside];
}
/** 添加图片按钮 */
- (void)add {
    if ([self.delegate respondsToSelector:@selector(addPicture:)]) {
        [self.delegate addPicture:self];
    }
}
/** 删除图片按钮 */
- (void)remove {
    if ([self.delegate respondsToSelector:@selector(removePicture:)]) {
        [self.delegate removePicture:self];
    }
}



YHPPictureChoiceController

#import "YHPPictureChoiceController.h"
#import "YHPPictrueChoicesFlowLayout.h"
#import "YHPPictureChoiceCell.h"
#import "UIImage+Extension.h"
#import <MobileCoreServices/MobileCoreServices.h>
/** 决定选择多少张图片 */
#define kArrayPictureMaxCount 4
/** 遵守代理协议 */
@interface YHPPictureChoiceController ()<YHPPictureChoiceCellDelegate,UIImagePickerControllerDelegate,UINavigationControllerDelegate>
/** 自定义流布局 */
@property (nonatomic, strong) YHPPictrueChoicesFlowLayout *layout;
/** picture数组 */
@property (nonatomic, strong) NSMutableArray *arrayPicture;
/** 已选照片索引 */
@property (nonatomic) NSInteger  selectedIndex;

@end

@implementation YHPPictureChoiceController
/** 注册cell重用标识 */
static NSString * YHPPICTURECHOICECELL = @"YHPPictureChoiceCell";
/** picture数组 */
-(NSMutableArray *)arrayPicture {
    if (!_arrayPicture) {
        _arrayPicture = [[NSMutableArray alloc]init];
//        [_arrayPicture addObject:[UIImage imageNamed:@"compose_pic_add"]];
    }
    return _arrayPicture;
}
/** 懒加载layout */
-(YHPPictrueChoicesFlowLayout *)layout {
    if(_layout == nil) {
        _layout = [[YHPPictrueChoicesFlowLayout alloc]init];
    }
    return _layout;
}
/** 重写init方法 */
- (instancetype)init
{
    self = [super initWithCollectionViewLayout:self.layout];
    if (self) {
        
    }
    return self;
}
/** viewDidLoad */
- (void)viewDidLoad {
    [super viewDidLoad];
    self.collectionView.backgroundColor = [UIColor whiteColor];
    /** 注册cell */
    [self.collectionView registerClass:[YHPPictureChoiceCell class] forCellWithReuseIdentifier:YHPPICTURECHOICECELL];
}
#pragma mark - 数据源方法
/** 组数 */
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return 1;
}
/** 每组多少个Item */
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    /** 决定选择多少张图片 */
    if (self.arrayPicture.count >= kArrayPictureMaxCount) {
        return kArrayPictureMaxCount;
    }
    return self.arrayPicture.count + (self.arrayPicture.count == kArrayPictureMaxCount ? 0 : 1);
}
/** 返回某组某个cell */
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    YHPPictureChoiceCell * cell = [collectionView dequeueReusableCellWithReuseIdentifier:YHPPICTURECHOICECELL forIndexPath:indexPath];
    cell.selected = NO;
    /** 设置代理 */
    cell.delegate = self;
    /** 根据indexpath.item来判断 */
    if (indexPath.item == 0) {
        /** cell.addBtn设置图片为固定加号图片 removeBtn隐藏 */
        [cell.addBtn setImage:[UIImage imageNamed:@"compose_pic_add"] forState:UIControlStateNormal];
        cell.removeBtn.hidden = YES;
        [cell.addBtn setBackgroundColor:[UIColor redColor]];
//        cell.addBtn.userInteractionEnabled = YES;
    } else {
        if (self.arrayPicture.count > 0) {
            /** 如果不让removeBtn显示 由于cell 复用问题 第三个以后就会没有removeBtn */
            cell.removeBtn.hidden = NO;
//            cell.addBtn.userInteractionEnabled = NO;
            [cell.addBtn setImage:self.arrayPicture[indexPath.item - 1] forState:UIControlStateNormal];
        }
    }
    /** 设置addBtn用户交互 根据removeBtn是否隐藏 */
    cell.addBtn.userInteractionEnabled = cell.removeBtn.hidden;
    return cell;
}
/** 设置组间距 */
- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout insetForSectionAtIndex:(NSInteger)section {
    /** 上 左 下 右 */
    return  UIEdgeInsetsMake(10, 10, 0, 10);
}
/** 隐藏状态栏 */
-(BOOL)prefersStatusBarHidden {
    return YES;
}
#pragma mark 实现代理方法
/** 添加图片 */
- (void)addPicture:(YHPPictureChoiceCell *)cell {
    if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {
        NSLog(@"不允许打开相册");
        return;
    }
    /** 记录当前选中的cell */
    self.selectedIndex = (NSInteger)[self.collectionView indexPathForCell:cell];
    /** 创建图片选择控制器 */
    UIImagePickerController * picker = [[UIImagePickerController alloc]init];
    /** 设置代理为自己 */
    picker.delegate = self;
    /** 允许编辑 */
    picker.allowsEditing = YES;
    /** modal出图片选择控制器 */
    [self presentViewController:picker animated:YES completion:nil];
}
/** 移除图片 */
- (void)removePicture:(YHPPictureChoiceCell *)cell {
//    NSLog(@"remove");
    // 1. 获取照片索引
    NSIndexPath * indexpath = [self.collectionView indexPathForCell:cell];
    // 2. 判断索引是否超出上限
    if (indexpath.item > self.arrayPicture.count + 1) {
        return;
    } else if (self.arrayPicture.count > 0) {
        /** 移除选中的cell */
        [self.arrayPicture removeObjectAtIndex:(indexpath.item - 1)];
    }
    /** 刷新数据 */
    [self.collectionView reloadData];
}

#pragma mark - UIImagePickerControllerDelegate
/** 选择完毕获取到图片的代理方法 */
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info {
    /** 将图片存入数组 */
    UIImage * scaleimage = info[UIImagePickerControllerEditedImage];
    scaleimage = [scaleimage scaleImageWithWidth:600];
    /** 如果当前索引>数组总数 不添加 */
    if (self.selectedIndex  >= self.arrayPicture.count) {
        [self.arrayPicture addObject:scaleimage];
    } else {
    /** 否则添加 */
        self.arrayPicture[(NSInteger)_selectedIndex] = scaleimage;
    }
    /** 刷新数据 */
    [self.collectionView reloadData];
    /** dismiss控制器 */
    [self dismissViewControllerAnimated:YES completion:nil];
}
@end


UIImage分类

#import "UIImage+Extension.h"
@implementation UIImage (Extension)
- (instancetype)scaleImageWithWidth:(CGFloat)width {
    if (width > self.size.width) {
        return self;
    }
    CGFloat height = self.size.height * width / self.size.width;
    CGRect rect = CGRectMake(0, 0, width, height);
    /** 开启上下文 */
    UIGraphicsBeginImageContext(rect.size);
    /** 绘制 */
    [self drawInRect:rect];
    /** 取结果 */
    UIImage * image = UIGraphicsGetImageFromCurrentImageContext();
    /** 关闭上下文 */
    UIGraphicsEndPDFContext();
    return image;
}