NSUserDefaults-优快云博客

本文链接：https://blog.youkuaiyun.com/jiaxin_1105/article/details/52299750

一、NSUserDefaults简介

1、NSUserDefaults是数据持久化的一种，可以将少量的数据保存在本地。其本质是将数据记录在plist文件中，当应用被删除，plist文件相应的会被删除，数据也就不存在了。
2、NSUserDefaults是系统提供的一个单例类，通过类方法standardUserDefaults可以获取NSUserDefaults单例。在项目中，我们可以用NSUserDefaults来保存跟用户相关的一些基本信息，比如头像、昵称、电话号码、地址等。
3、NSUserDefaults其本质是将数据保存在plist文件中，所以只能存储plist文件支持的数据类型，包括：NSData、NSString、NSNumber、NSDate、NSArray、NSDictionary。如果需要存储plist文件不支持的类型，比如说存储图片，就需要把图片归档成NSDate类型，再存入plist文件中。

二、NSUserDefaults基本用法

1、存储数据

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//数据写入NSUserdefaults</span>
- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)btnWrite:(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span>)sender
{
    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获取NSUserDefaults的单例</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSUserDefaults</span> *defaults = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSUserDefaults</span> standardUserDefaults];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存字符串类型的数据</span>
    [defaults setObject:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"火山"</span> forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存字典类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> *dictInfo = @{@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"张三"</span>,@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age"</span>:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"20"</span>};
    [defaults setObject:dictInfo forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"dictInfo"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存数组类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSArray</span> *arr = @[@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"1"</span>,@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"2"</span>,@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"3"</span>];
    [defaults setObject:arr forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"arr"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存整型类型的数据</span>
    [defaults setInteger:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">20</span> forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存bool类型的数据</span>
    [defaults setBool:<span class="hljs-literal" style="color: rgb(0, 102, 102); box-sizing: border-box;">YES</span> forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存float类型的数据</span>
    [defaults setFloat:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.123456</span> forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"price"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存Double类型的数据</span>
    [defaults setDouble:<span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.1234567123456712</span> forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"total"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存url类型的数据</span>
    [defaults setURL:[<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSURL</span> URLWithString:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"http://www.baidu.com"</span>] forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"url"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存NSData类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIImage</span> *image = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIImage</span> imageNamed:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"test.jpg"</span>];
    NSData *data = UIImageJPEGRepresentation(image, <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">0.5</span>);
    [defaults setObject:data forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"image"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//保存NSDate类型的数据</span>
    [defaults setObject:[<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDate</span> date] forKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"date"</span>];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//强制存储</span>
    [defaults synchronize];
}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li></ul>

2、读取数据

<code class="hljs objectivec has-numbering" style="display: block; padding: 0px; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-radius: 0px; word-wrap: normal; background: transparent;"><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//从NSUserDefaults读取数据</span>
- (<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span>)btnRead:(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">id</span>)sender
{
    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//获取NSUserDefaults的单例</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSUserDefaults</span> *defaults = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSUserDefaults</span> standardUserDefaults];

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取字符串类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSString</span> *name = [defaults objectForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"name"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,name);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取字典类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDictionary</span> *dictInfo = [defaults dictionaryForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"dictInfo"</span>];
    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//或者 NSDictionary *dictInfo = [defaults objectForKey:@"dictInfo"];</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,dictInfo);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取数组类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSArray</span> *arr = [defaults arrayForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"arr"</span>];
   <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 或者 NSArray *arr = [defaults objectForKey:@"arr"];</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,arr);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取bool类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">BOOL</span> value = [defaults boolForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"key"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,[<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSNumber</span> numberWithBool:value]);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取整型类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSInteger</span> age = [defaults integerForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"age"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%ld"</span>,age);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取float类型的数据</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">float</span> price = [defaults floatForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"price"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%f"</span>,price);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取double类型的数据</span>
    <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">double</span> total = [defaults doubleForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"total"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,[<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSNumber</span> numberWithDouble:total]);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取url类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSURL</span> *url = [defaults URLForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"url"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,url);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取NSData类型的数据</span>
    NSData *data = [defaults dataForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"image"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIImage</span> *image = [<span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">UIImage</span> imageWithData:data];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,image);

    <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">//读取NSDate类型的数据</span>
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSDate</span> *date = [defaults objectForKey:@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"date"</span>];
    <span class="hljs-built_in" style="color: rgb(102, 0, 102); box-sizing: border-box;">NSLog</span>(@<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"%@"</span>,date);

}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right; background-color: rgb(238, 238, 238);"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li><li style="box-sizing: border-box; padding: 0px 5px;">39</li><li style="box-sizing: border-box; padding: 0px 5px;">40</li><li style="box-sizing: border-box; padding: 0px 5px;">41</li><li style="box-sizing: border-box; padding: 0px 5px;">42</li><li style="box-sizing: border-box; padding: 0px 5px;">43</li><li style="box-sizing: border-box; padding: 0px 5px;">44</li><li style="box-sizing: border-box; padding: 0px 5px;">45</li><li style="box-sizing: border-box; padding: 0px 5px;">46</li><li style="box-sizing: border-box; padding: 0px 5px;">47</li><li style="box-sizing: border-box; padding: 0px 5px;">48</li><li style="box-sizing: border-box; padding: 0px 5px;">49</li><li style="box-sizing: border-box; padding: 0px 5px;">50</li><li style="box-sizing: border-box; padding: 0px 5px;">51</li></ul>

NSUserDefaults非常好用，并不需要用户在程序中设置NSUserDefaults的全局变量，需要在哪里使用NSUserDefaults的数据，那么就在哪里创建一个NSUserDefaults对象，然后进行读或者写操作。