一般iOS在UITableView没有数据的时候为了界面好看一点,UI会给这些没有数据的页面设计一些占位图,有的时候是纯图片,有的时候会有一些按钮操作。
实现也很简单就是为UITableView 添加一个Category
#import <UIKit/UIKit.h>
NS_ASSUME_NONNULL_BEGIN
@protocol DTableViewPlaceHolderDelegate <NSObject>
@required
/**
无数据占位图
@return 占位图
*/
- (UIView *)makePlaceHolderView;
@optional
/**
出现占位图的时候TableView是否能拖动
@return BOOL
*/
- (BOOL)enableScrollWhenPlaceHolderViewShowing;
@end
@interface UITableView (PlaceHolder)
@property (nonatomic, weak, nullable) id <DTableViewPlaceHolderDelegate> placeHolderDelegate;
- (void)d_reloadData;
@end
#import "UITableView+PlaceHolder.h"
#import <objc/runtime.h>
@interface UITableView ()
/**占位图*/
@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);
}
-(id)placeHolderDelegate{
return objc_getAssociatedObject(self, @selector(placeHolderDelegate));
}
- (void)setPlaceHolderDelegate:(id<DTableViewPlaceHolderDelegate>)placeHolderDelegate{
objc_setAssociatedObject(self, @selector(placeHolderDelegate), placeHolderDelegate, 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;
// 获取sections
if ([src respondsToSelector: @selector(numberOfSectionsInTableView:)]) {
sections = [src numberOfSectionsInTableView:self];
}
// 获取rows
for (int i = 0; i<sections; ++i) {
NSInteger rows = [src tableView:self numberOfRowsInSection:i];
// 如果rows不为零
if (rows > 0) {
isEmpty = NO;
break;
}
}
// 如果rows为空
if (isEmpty) {
// 模式ScrollView可以滚动
BOOL scrollEnabled = YES;
if ([self respondsToSelector:@selector(enableScrollWhenPlaceHolderViewShowing)]) {
scrollEnabled = [[self performSelector:@selector(enableScrollWhenPlaceHolderViewShowing)] boolValue];
}
else if ([self.delegate respondsToSelector:@selector(enableScrollWhenPlaceHolderViewShowing)]) {
scrollEnabled = [[self.delegate performSelector:@selector(enableScrollWhenPlaceHolderViewShowing)] boolValue];
}
self.scrollEnabled = scrollEnabled;
// 移除placeHolderView
[self.placeHolderView removeFromSuperview];
// 获取placeHolderView
if ([self respondsToSelector:@selector(makePlaceHolderView)]) {
self.placeHolderView = [self performSelector:@selector(makePlaceHolderView)];
}
if ( [self.placeHolderDelegate respondsToSelector:@selector(makePlaceHolderView)]) {
self.placeHolderView = [self.placeHolderDelegate makePlaceHolderView];
}
self.placeHolderView.frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
[self addSubview:self.placeHolderView];
}
else {
// rows不为空 移除placeHolderView
[self.placeHolderView removeFromSuperview];
self.placeHolderView = nil;
// 设置TableView 可滚动
self.scrollEnabled = YES;
}
}
@end
使用,现实DTableViewPlaceHolderDelegate
self.tableView.placeHolderDelegate = self;
// 刷新数据调用
[self.tableView d_reloadData];
- (UIView *)makePlaceHolderView {
return [TaskPlaceholder loadXibView];;
}
Xib/纯代码的View都可以。如果有按钮事件就在自定义的View里面加block即可
- (UIView *)makePlaceHolderView {
TaskPlaceholder *view = [TaskPlaceholder loadXibView];
view.emptyOverlayClicked = ^{
// 做一些按钮操作
};
return view;
}
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