[示例]NSDictionary编程题-字典的排序应用(iOS7班)

代码：

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    @autoreleasepool {
        //将字典的key从Z->A排序，按排序后的key的顺序，输出value，将value按字符串输出
        NSDictionary *dict=@{@"R":@"e",
                             @"T":@"e",
                             @"D":@"b",
                             @"S":@"u",
                             @"K":@"a",
                             @"A":@"s",
                             @"O":@" ",
                             @"N":@"p",
                             @"B":@"b",
                             @"J":@"u",
                             @"F":@" ",
                             @"U":@"t",
                             @"H":@"l",
                             @"E":@"j",
                             @"Z":@"s",};

        NSArray *arr=[dict allKeys];
        NSComparator comp=^(id obj1,id obj2){
            NSComparisonResult result=[obj2 compare:obj1];
            return result;
        };
        NSArray *sortArr=[arr sortedArrayUsingComparator:comp];
        for(NSString *str in sortArr) {
            NSLog(@"key=%@,value=%@",str,dict[str]);
        }

    }
    return ;
}