检查NSDictionary是否为空

本文介绍了检查NSDictionary是否为空的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我想检查 NSDictionary 是否为空。我是这样做的。

I want to check if an NSDictionary is empty. I am doing it like this.

mutDictValues = [[[NSUserDefaults standardUserDefaults] objectForKey:@"dicValues"]mutableCopy]; NSLog(@"dictValues are %@",mutDictValues); if(mutDictValues == NULL){ arrCities = [[NSMutableArray alloc]init]; NSLog(@"no cities seleceted"); }else{ arrCities = [[NSMutableArray alloc]init]; arrCities = [mutDictValues objectForKey:@"cities"]; [self placeCities]; }

但是这条线上的alwasy崩溃 arrCities = [ mutDictValues objectForKey：@cities]; ，出现以下错误：

But it alwasy crashes on this line arrCities = [mutDictValues objectForKey:@"cities"]; with the following error:

-[__NSCFConstantString objectForKey:]:

有人可以帮我吗？

推荐答案

从NSUserDefaults检索字典值时，字典自动转换为字符串，这是崩溃的原因检查字典使用

While retrieving the dictionary values from NSUserDefaults that dictionary automatically converted into string that is the reason for getting crashed and for checking dictionary use [dictionary count];

编辑： - 使用dictionaryForKey：方法

NSDictionary *dict =[[NSDictionary alloc]initWithObjectsAndKeys:@"hi",@"one",nil]; [[NSUserDefaults standardUserDefaults] setObject:dict forKey:@"dic"]; NSDictionary *dictn = [[NSUserDefaults standardUserDefaults] dictionaryForKey:@"dic"]; NSLog(@"%@",[dictn objectForKey:@"one"]);