ios UITableView实现无数据加载占位图片

+ (void)swizzleInstanceSelector:(SEL)originalSel      WithSwizzledSelector:(SEL)swizzledSel {  Method originMethod = class_getInstanceMethod(self, originalSel);  Method swizzedMehtod = class_getInstanceMethod(self, swizzledSel);  BOOL methodAdded = class_addMethod(self, originalSel, method_getImplementation(swizzedMehtod), method_getTypeEncoding(swizzedMehtod));  if (methodAdded) {    class_replaceMethod(self, swizzledSel, method_getImplementation(originMethod), method_getTypeEncoding(originMethod));  }else{    method_exchangeImplementations(originMethod, swizzedMehtod);  }}

+ (void)load {  static dispatch_once_t onceToken;  dispatch_once(&onceToken, ^{    [self swizzleInstanceSelector:@selector(reloadData) WithSwizzledSelector:@selector(kk_reloadData)];  });}

- (void)kk_reloadData {  [self kk_checkEmpty];  [self kk_reloadData];}

- (void)kk_checkEmpty {  BOOL isEmpty = YES;  id<UITableViewDataSource> src = self.dataSource;  NSInteger sections = 1;  if ([src respondsToSelector:@selector(numberOfSectionsInTableView:)]) {    sections = [src numberOfSectionsInTableView:self];  }  for (int i = 0; i < sections; i++) {    NSInteger rows = [src tableView:self numberOfRowsInSection:i];    if (rows) {      isEmpty = NO;    }  }  if (isEmpty) {//数据为空，在这里添加视图  }else{//数据不为空，在这里一处视图  }}

@property (nonatomic, strong) UIView *placeHolderView;

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

if (isEmpty) {//数据为空，在这里添加视图}else{//数据不为空，在这里一处视图}

if (isEmpty) {    [self.placeHolderView removeFromSuperview];    [self addSubview:self.placeHolderView];  }else{    [self.placeHolderView removeFromSuperview];  }

_tableView.placeHolderView = [[UIView alloc] init];