2018-06-09 NSDictionary

字典Dictionary是集合類的一種。
集合：數(shù)組array、字典dictionary、set；數(shù)組是有順序的，且元素可以重復(fù)的；字典是沒有順序的，鍵是唯一的，值是可重復(fù)的；set是無序的，且不可重復(fù)的。
字典就是以鍵值對(duì)的形式存在的數(shù)據(jù)集合；
字典的鍵是唯一的；
字典的值是可重復(fù)的；
字典的鍵值是一一對(duì)應(yīng)的，即有多少個(gè)鍵，就有多少個(gè)值；
字典中的鍵值對(duì)是沒有順序的；
比如：身份證 & 姓名；身份證就是鍵，姓名就是值。

字典分不可變字典，可變字典兩類。
注意：
鍵值都是對(duì)象類型，不能是基礎(chǔ)數(shù)值；

特別是鍵，一般都是string對(duì)象設(shè)置；

[objc] view plaincopy

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  1. // 不可變字典
  2. // 初始化
  3. NSDictionary *dict001 = [[NSDictionary alloc] initWithObjectsAndKeys:@"張紹鋒", @"name", @"男", @"sex", nil nil];
  4. NSLog(@"\n dict001 = %@ \n", dict001);

[objc] view plaincopy

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  1. // 屬性

  2. // 1 個(gè)數(shù)

  3. NSInteger count = dict001.count;

  4. NSLog(@"\n count = %ld \n", count);

  5. // 2 所有的鍵

  6. NSArray *keyArray = dict001.allKeys;

  7. NSLog(@"\n");

  8. for (NSString *string in keyArray)

  9. {

  10. NSLog(@"string = %@", string);

  11. }

  12. // 3 所有的值

  13. NSArray *valueArray = dict001.allValues;

  14. NSLog(@"\n");

  15. for (NSString *string in valueArray)

  16. {

  17. NSLog(@"string = %@", string);

  18. }

[objc] view plaincopy

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  1. // 字典操作
  2. // 獲取鍵對(duì)應(yīng)的值
  3. NSString *value = [dict001 objectForKey:@"name"];
  4. NSLog(@"\n");
  5. NSLog(@"name = %@", value);

[objc] view plaincopy

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  1. // 可變字典
  2. NSMutableDictionary *dict002 = [NSMutableDictionary dictionaryWithDictionary:dict001];
  3. NSLog(@"\n dict002 = %@ \n", dict002);

[objc] view plaincopy

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  1. // 添加對(duì)象

  2. // 1 setobject時(shí)，值必須是非空對(duì)象類型，如果值是非對(duì)象類型，則報(bào)錯(cuò)

  3. [dict002 setObject:@"大學(xué)比業(yè)" forKey:@"education"];

  4. //[dict002 setObject:nil forKey:@"education"]; // 編譯報(bào)錯(cuò)

  5. NSLog(@"\n dict002 = %@ \n", dict002);

  6. // 2 setvalue時(shí)，不管值是不是對(duì)象類型，都不會(huì)報(bào)錯(cuò)，但對(duì)象不會(huì)添加到字典中

  7. [dict002 setValue:@"高級(jí)電工" forKey:@"job"];

  8. //[dict002 setValue:nil forKey:@"job"]; // 可正常編譯運(yùn)行，但對(duì)象不會(huì)添加到字典中

  9. NSLog(@"\n dict002 = %@ \n", dict002);

[objc] view plaincopy

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  1. // 替換指定鍵對(duì)應(yīng)的值
  2. [dict002 setValue:@"iOS Dve" forKey:@"job"];
  3. NSLog(@"\n dict002 = %@ \n", dict002);

[objc] view plaincopy

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<embed id="ZeroClipboardMovie_15" src="https://csdnimg.cn/public/highlighter/ZeroClipboard.swf" loop="false" menu="false" quality="best" bgcolor="#ffffff" width="16" height="16" name="ZeroClipboardMovie_15" align="middle" allowscriptaccess="always" allowfullscreen="false" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" flashvars="id=15&width=16&height=16" wmode="transparent" style="box-sizing: border-box; outline: 0px; word-break: break-all;">

  1. // 刪除指定鍵對(duì)應(yīng)的值

  2. // 1 刪除指定鍵對(duì)應(yīng)的值

  3. [dict002 removeObjectForKey:@"job"];

  4. NSLog(@"\n dict002 = %@ \n", dict002);

  5. // 2 刪除指定鍵數(shù)組對(duì)應(yīng)的值

  6. NSArray *keys = @[@"education", @"sex"];

  7. [dict002 removeObjectsForKeys:keys];

  8. NSLog(@"+\n dict002 = %@ \n", dict002);

  9. // 3 刪除所有的鍵值

  10. [dict002 removeAllObjects];

  11. NSLog(@"-\n dict002 = %@ \n", dict002);

[objc] view plaincopy

<embed id="ZeroClipboardMovie_8" src="https://csdnimg.cn/public/highlighter/ZeroClipboard.swf" loop="false" menu="false" quality="best" bgcolor="#ffffff" width="16" height="16" name="ZeroClipboardMovie_8" align="middle" allowscriptaccess="always" allowfullscreen="false" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" flashvars="id=8&width=16&height=16" wmode="transparent" style="box-sizing: border-box; outline: 0px; word-break: break-all;">

<embed id="ZeroClipboardMovie_16" src="https://csdnimg.cn/public/highlighter/ZeroClipboard.swf" loop="false" menu="false" quality="best" bgcolor="#ffffff" width="16" height="16" name="ZeroClipboardMovie_16" align="middle" allowscriptaccess="always" allowfullscreen="false" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer" flashvars="id=16&width=16&height=16" wmode="transparent" style="box-sizing: border-box; outline: 0px; word-break: break-all;">

  1. // 重新初始化值
  2. [dict002 setDictionary:dict001];
  3. NSLog(@"\n dict002 = %@ \n", dict002);
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