iOS自定义控件：自定义TableView、CollectionView空数据占位图-白红宇

最近由于业务需求，需要封装这样的一个提示页面。看了网上方法感觉都大同小异，其中是很好的一个库，但是对我个人而言有点大财小用了。所以就借鉴一下其方法，自己封装一个。感觉有更高的自定义性吧。（我是初学者，请大佬爱护，勿喷）一、封装代码：利用UIScrollView的分类实现

#import 
    
     NS_ASSUME_NONNULL_BEGIN@interface UIScrollView (WD_NoData)// 需要显示的占位页面@property (nonatomic, strong) UIView *noDataView;@endNS_ASSUME_NONNULL_END复制代码

实现代码

#import "UIScrollView+WD_NoData.h"#import 
    
     static char *noDataViewKey = "noDataViewKey";@implementation UIScrollView (WD_NoData)/** 交换方法 @param sel1 原方法 @param sel2 自定义方法 @param cls 类 */void exchangeSelector(SEL sel1, SEL sel2, Class cls) {    Class class = [cls class];    Method originalMethod = class_getInstanceMethod(class, sel1);    Method swizzledMethod = class_getInstanceMethod(class, sel2);    BOOL success = class_addMethod(class, sel1, method_getImplementation(swizzledMethod), method_getTypeEncoding(swizzledMethod));    if (success) {        class_replaceMethod(class, sel2, method_getImplementation(originalMethod), method_getTypeEncoding(originalMethod));    } else {        method_exchangeImplementations(originalMethod, swizzledMethod);    }}#pragma mark =============== Setter ===============- (void)setNoDataView:(UIView *)noDataView {    static dispatch_once_t onceToken;    dispatch_once(&onceToken, ^{        exchangeSelector(@selector(reloadData), @selector(wd_reloadData), [self class]);    });        objc_setAssociatedObject(self, noDataViewKey, noDataView, OBJC_ASSOCIATION_RETAIN_NONATOMIC);}#pragma mark =============== Getter ===============- (UIView *)noDataView {    UIView *noDataView = objc_getAssociatedObject(self, noDataViewKey);    noDataView.frame = self.frame;    return noDataView;}- (void)wd_reloadData {    [self wd_reloadData];    [self wd_checkData];}#pragma mark =============== 获取数据 ===============- (void)wd_checkData {    NSInteger items = 0;        if (![self respondsToSelector:@selector(dataSource)]) {        return;    }        // UITableView support    if ([self isKindOfClass:[UITableView class]]) {                UITableView *tableView = (UITableView *)self;        id 
     
       dataSource = tableView.dataSource;                NSInteger sections = 1;                if (dataSource && [dataSource respondsToSelector:@selector(numberOfSectionsInTableView:)]) {            sections = [dataSource numberOfSectionsInTableView:tableView];        }                if (dataSource && [dataSource respondsToSelector:@selector(tableView:numberOfRowsInSection:)]) {            for (NSInteger section = 0; section < sections; section++) {                items += [dataSource tableView:tableView numberOfRowsInSection:section];            }        }    }    // UICollectionView support    else if ([self isKindOfClass:[UICollectionView class]]) {                UICollectionView *collectionView = (UICollectionView *)self;        id 
      
        dataSource = collectionView.dataSource;                NSInteger sections = 1;                if (dataSource && [dataSource respondsToSelector:@selector(numberOfSectionsInCollectionView:)]) {            sections = [dataSource numberOfSectionsInCollectionView:collectionView];        }                if (dataSource && [dataSource respondsToSelector:@selector(collectionView:numberOfItemsInSection:)]) {            for (NSInteger section = 0; section < sections; section++) {                items += [dataSource collectionView:collectionView numberOfItemsInSection:section];            }        }    }        if ( items == 0 ) {        [self.superview addSubview:self.noDataView];    } else {        [self.noDataView removeFromSuperview];    }}@end复制代码

二、使用方法

#import "UIScrollView+WD_NoData.h"// 自定义页面#import "WDTestEmptyView.h"复制代码

//示例的视图 WDTestEmptyView *view = [NSBundle.mainBundle loadNibNamed:@"WDTestEmptyView" owner:self options:nil].firstObject;// 设置视图self.tableView.noDataView = view;复制代码

三、效果图