创建UITableView子类，重写layoutSubviews:方法
- (void)layoutSubviews {
[super layoutSubviews];
[[self.subviews filteredArrayUsingPredicate:[NSPredicate predicateWithBlock:^BOOL(id _Nullable evaluatedObject, NSDictionary<NSString *,id> * _Nullable bindings) {
if ([NSStringFromClass([evaluatedObject class]) rangeOfString: @"ShadowView"].location != NSNotFound) {
return YES;
}
return NO;
}]] enumerateObjectsUsingBlock:^(__kindof UIView * _Nonnull obj, NSUInteger idx, BOOL * _Nonnull stop) {
obj.alpha = 0.2;
}];
}
