iOS开发之UITableView数据为空的提示页面

经常用UITableView，一定会遇到数据为空的情况，这时需要在空页面上放一个图片和一行文字提示数据为空，下面整理了两种方法来实现这个功能。

第一个是继承UITableView，在新类中集成图片和文字

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

@interface WFEmptyTableView : UITableView

@property (nonatomic, assign) BOOL showEmptyTipView; // 是否显示背景提示文字
@property (nonatomic, assign) NSInteger vOffset;
@property (nonatomic, copy) NSString *tipString;     // 提示文字
@property (nonatomic, copy) NSString *tipImageName;  // 提示图片

@end

具体实现

#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

还有一种方法，是用Category

#import <UIKit/UIKit.h>

@interface UITableView (WFEmpty)

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

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

@end

具体实现

#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