如何在数组中的字典中获取值的索引

Question

像这样的数组:

    <array>
      <dict>
        <key>Place</key>
        <string>A</string>
        <key>Name</key>
        <string>B</string>
        <key>Object</key>
        <string>C</string>
      </dict>
      <dict>
        <key>Place</key>
        <string>D</string>
        <key>Name</key>
        <string>E</string>
        <key>Object</key>
        <string>F</string>
      </dict>
      <dict>
        <key>Place</key>
        <string>X</string>
        <key>Name</key>
        <string>Y</string>
        <key>Object</key>
        <string>Z</string>
      </dict>
      <dict>
        <key>Place</key>
        <string>S</string>
        <key>Name</key>
        <string>T</string>
        <key>Object</key>
        <string>U</string>
      </dict>
      ...
    </array>

//由于某种原因,我通过删除原始顶级数组来简化此示例的级别.现在它们看起来像一个由一些词典组成的数组.

例如,[[objectArray objectAtIndex:i] valueForKey:@"Place"]如果像X一样,可以获得任何值

然后,在另一个仍然相同的地方.m,只需要利用X来反向获取X所在字典的索引.因为在这个地方,只能访问objectArray.

什么是正确的方法应该做什么？

Answer 1

再次使用KVC!

拥有阵列时有3行:D

短

NSArray *arrayWithDicts = @[d1,d2,d3,d4];//your array!

NSArray *arrayWithPlaces = [arrayWithDicts valueForKey:@"Place"];
NSUInteger index = [arrayWithPlaces indexOfObject:@"cologne"];
NSDictionary *dict = index != NSNotFound ? arrayWithDicts[index] : nil;

完整的例子

#import <Foundation/Foundation.h>

int main(int argc, char *argv[]) {
    @autoreleasepool {
        //build demo array
        NSDictionary *d1 = @{@"Place": @"clackson"};
        NSDictionary *d2 = @{@"Place": @"berlin"};
        NSDictionary *d3 = @{@"Place": @"cologne"};
        NSDictionary *d4 = @{@"Place": @"mclean"};
        NSArray *arrayWithDicts = @[d1,d2,d3,d4];

        //get all places
        NSArray *arrayWithPlaces = [arrayWithDicts valueForKey:@"Place"];
        assert(arrayWithDicts.count == arrayWithPlaces.count);

        //find place and get dict
        NSUInteger index = [arrayWithPlaces indexOfObject:@"cologne"];
        NSDictionary *dict = index != NSNotFound ? arrayWithDicts[index] : nil;

        NSLog(@"%@", dict);     
    }
}