在使用TableView的時(shí)候，經(jīng)常會(huì)遇到一些無數(shù)據(jù)需要用到占位圖的情況，所以就寫一個(gè)控件來實(shí)現(xiàn)。
思路：使用UITableView Category來實(shí)現(xiàn)，由于占位圖式樣多種多樣，所以控件就不用考慮很多情況，把占位圖交給外部實(shí)現(xiàn)，控件內(nèi)部只處理有數(shù)據(jù)和沒有數(shù)據(jù)顯示占位圖即可。

#import <UIKit/UIKit.h>

NS_ASSUME_NONNULL_BEGIN

@protocol DTableViewPlaceHolderDelegate <NSObject>

@required

/**
 無數(shù)據(jù)占位圖
 @return 占位圖
 */
- (UIView *)makePlaceHolderView;

@optional

/**
 出現(xiàn)占位圖的時(shí)候TableView是否能拖動(dòng)
 @return BOOL
 */
- (BOOL)enableScrollWhenPlaceHolderViewShowing;

@end

@interface UITableView (PlaceHolder)

- (void)d_reloadData;

@end

NS_ASSUME_NONNULL_END

#import "UITableView+PlaceHolder.h"
#import <objc/runtime.h>

@interface UITableView ()

/**占位圖*/
@property (nonatomic, strong) UIView *placeHolderView;

@end


@implementation UITableView (PlaceHolder)

- (UIView *)placeHolderView {
    return objc_getAssociatedObject(self, @selector(placeHolderView));
}

- (void)setPlaceHolderView:(UIView *)placeHolderView {
    objc_setAssociatedObject(self, @selector(placeHolderView), placeHolderView, OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}

- (void)d_reloadData {
    [self reloadData];
    [self d_checkEmpty];
}

- (void)d_checkEmpty {
    BOOL isEmpty = YES;
    
    id<UITableViewDataSource> src = self.dataSource;
    NSInteger sections = 1;
    // 獲取sections
    if ([src respondsToSelector: @selector(numberOfSectionsInTableView:)]) {
        sections = [src numberOfSectionsInTableView:self];
    }
    // 獲取rows
    for (int i = 0; i<sections; ++i) {
        NSInteger rows = [src tableView:self numberOfRowsInSection:i];
        // 如果rows不為零
        if (rows > 0) {
            isEmpty = NO;
            break;
        }
        
    }
    
    // 如果rows為空
    if (isEmpty) {
    
        // 默認(rèn)ScrollView可以滾動(dòng)
        BOOL scrollEnabled = YES;
        if ([self respondsToSelector:@selector(enableScrollWhenPlaceHolderViewShowing)]) {
            scrollEnabled = [self performSelector:@selector(enableScrollWhenPlaceHolderViewShowing)];
        }
        else if ([self.delegate respondsToSelector:@selector(enableScrollWhenPlaceHolderViewShowing)]) {
            scrollEnabled = [self.delegate performSelector:@selector(enableScrollWhenPlaceHolderViewShowing)];
        }
        self.scrollEnabled = scrollEnabled;
        
        // 移除placeHolderView
        [self.placeHolderView removeFromSuperview];
        // 獲取placeHolderView
        if ([self respondsToSelector:@selector(makePlaceHolderView)]) {
            self.placeHolderView = [self performSelector:@selector(makePlaceHolderView)];
        }
        else if ( [self.delegate respondsToSelector:@selector(makePlaceHolderView)]) {
            self.placeHolderView = [self.delegate performSelector:@selector(makePlaceHolderView)];
        }
        self.placeHolderView.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
        [self addSubview:self.placeHolderView];
    }
    else {
        // rows不為空 移除placeHolderView
        [self.placeHolderView removeFromSuperview];
        self.placeHolderView = nil;
        // 設(shè)置TableView 可滾動(dòng)
        self.scrollEnabled = YES;
    }
}

@end

使用時(shí)候只要調(diào)用d_reloadData方法即可。但是必須實(shí)現(xiàn)

- (UIView *)makePlaceHolderView ;

如果需要在沒有數(shù)據(jù)的時(shí)候讓TableView的拖動(dòng)不可用，需要實(shí)現(xiàn)

- (BOOL)enableScrollWhenPlaceHolderViewShowing{
    return NO;
}

Demo