iOS implements a prompt page when UITableView data is empty

Preface

It is believed that for iOS developers, UITableView is often used in the development process, and 1 will encounter the situation that the data is empty. At this time, you need to put a picture and a line of text on the empty page to indicate that the data is empty. Here are two ways to achieve this function.

The first is to inherit UITableView and integrate pictures and text into the new class

#import <UIKit/UIKit.h>
#import "Const.h"

@interface WFEmptyTableView : UITableView

@property (nonatomic, assign) BOOL showEmptyTipView; //  Whether to display background prompt text 
@property (nonatomic, assign) NSInteger vOffset;
@property (nonatomic, copy) NSString *tipString;  //  Prompt Text 
@property (nonatomic, copy) NSString *tipImageName; //  Tip Picture 

@end

Specific implementation

#import "WFEmptyTableView.h"

@implementation WFEmptyTableView {
 UIView *_customBackView;
 UIImageView *_tipImageView;
 UILabel *_label;
 CGRect _imageFrame;
 CGRect _labelFrame;
 double _scale;
}

- (WFEmptyTableView *)initWithFrame:(CGRect)frame style:(UITableViewStyle)style {
 self = [super initWithFrame:frame style:style];
 if (self) {
  [self setupViews];
 }
 return self;
}

- (void)setupViews {
 _customBackView = [[UIView alloc] initWithFrame:self.frame];
 _customBackView.backgroundColor = [UIColor yellowColor];

 _tipImageView = [[UIImageView alloc] initWithFrame:CGRectMake((kScreenWidth-200/2)/2, self.frame.size.height/3, 200/2, 200/2)];
 [_customBackView addSubview:_tipImageView];
 _imageFrame = _tipImageView.frame;

 _label = [[UILabel alloc] initWithFrame:CGRectMake(0, CGRectGetMaxY(_tipImageView.frame), kScreenWidth, 100)];

 _label.backgroundColor = [UIColor clearColor];
 _label.textAlignment = NSTextAlignmentCenter;
 _label.textColor = [UIColor lightGrayColor];
 _label.font = [UIFont systemFontOfSize:16];
 _label.lineBreakMode = NSLineBreakByCharWrapping;
 _label.numberOfLines = 0;
 [_customBackView addSubview:_label];
 _labelFrame = _label.frame;

}

- (void)setShowEmptyTipView:(BOOL)showEmptyTipView {
 _showEmptyTipView = showEmptyTipView;
 if (showEmptyTipView) {
  [self addSubview:_customBackView];
 } else {
  [_customBackView removeFromSuperview];
 }
}

- (void)setTipString:(NSString *)tipString {
 _tipString = tipString;

 NSMutableAttributedString * attributedString1 = [[NSMutableAttributedString alloc] initWithString:tipString];
 NSMutableParagraphStyle * paragraphStyle1 = [[NSMutableParagraphStyle alloc] init];
 [paragraphStyle1 setLineSpacing:15];
 [paragraphStyle1 setAlignment:NSTextAlignmentCenter];
 [attributedString1 addAttribute:NSParagraphStyleAttributeName value:paragraphStyle1 range:NSMakeRange(0, [tipString length])];
 [_label setAttributedText:attributedString1];

 [self resetFrame];
}

- (void)setTipImageName:(NSString *)tipImageName {
 _scale = 1;
 UIImage *image = [UIImage imageNamed:tipImageName];
 _scale = image.size.height*1.0 / image.size.width;
 _tipImageView.image = image;

 if (isnan(_scale)) {
  _scale = 1;
 }
 [self resetFrame];
}

- (void)setVOffset:(NSInteger)vOffset {
 _label.frame = CGRectMake(CGRectGetMinX(_label.frame), CGRectGetMinY(_label.frame)+vOffset, CGRectGetWidth(_label.frame), CGRectGetHeight(_label.frame));
 _tipImageView.frame = CGRectMake(CGRectGetMinX(_tipImageView.frame), CGRectGetMinY(_tipImageView.frame)+vOffset, CGRectGetWidth(_tipImageView.frame), CGRectGetHeight(_tipImageView.frame));
}

- (void)resetFrame {
 _tipImageView.frame = CGRectMake(0, CGRectGetMinY(_tipImageView.frame), 150, 150 * _scale);
 _tipImageView.center = CGPointMake(kScreenWidth / 2.0, _tipImageView.center.y);

 _label.frame = CGRectMake(CGRectGetMinX(_label.frame), CGRectGetMaxY(_tipImageView.frame), CGRectGetWidth(_label.frame), CGRectGetHeight(_label.frame));
}

@end

Another way is to use Category

#import <UIKit/UIKit.h>

@interface UITableView (WFEmpty)

@property (nonatomic, strong, readonly) UIView *emptyView;

-(void)addEmptyViewWithImageName:(NSString*)imageName title:(NSString*)title;

@end

Specific implementation

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

static char UITableViewEmptyView;

@implementation UITableView (WFEmpty)

@dynamic emptyView;

- (UIView *)emptyView
{
 return objc_getAssociatedObject(self, &UITableViewEmptyView);
}

- (void)setEmptyView:(UIView *)emptyView
{
 [self willChangeValueForKey:@"HJEmptyView"];
 objc_setAssociatedObject(self, &UITableViewEmptyView,
        emptyView,
        OBJC_ASSOCIATION_ASSIGN);
 [self didChangeValueForKey:@"HJEmptyView"];
}


-(void)addEmptyViewWithImageName:(NSString*)imageName title:(NSString*)title
{
 if (!self.emptyView)
 {
  CGRect frame = CGRectMake(0, 0, self.frame.size.width, self.frame.size.height);
  UIImage* image = [UIImage imageNamed:imageName];
  NSString* text = title;

  UIView* noMessageView = [[UIView alloc] initWithFrame:frame];
  noMessageView.backgroundColor = [UIColor clearColor];

  UIImageView *carImageView = [[UIImageView alloc] initWithFrame:CGRectMake((frame.size.width-image.size.width)/2, 60, image.size.width, image.size.height)];
  [carImageView setImage:image];
  [noMessageView addSubview:carImageView];

  UILabel *noInfoLabel = [[UILabel alloc] initWithFrame:CGRectMake(0, 160, frame.size.width, 20)];
  noInfoLabel.textAlignment = NSTextAlignmentCenter;
  noInfoLabel.textColor = [UIColor lightGrayColor];
  noInfoLabel.text = text;
  noInfoLabel.backgroundColor = [UIColor clearColor];
  noInfoLabel.font = [UIFont systemFontOfSize:20];
  [noMessageView addSubview:noInfoLabel];

  [self addSubview:noMessageView];

  self.emptyView = noMessageView;
 }

}

@end

summary

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