前言
相信对于iOS开发者们来说，在开发过程中，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
总结
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