对数组中的字典进行排序

原来字典
NSArray*arr=@[@{@"index":@"3",@"key":@"value"},
@{@"index":@"4",@"key":@"value"},
@{@"index":@"1",@"key":@"value"},
@{@"index":@"2",@"key":@"value"}];

要重新按照字典里的index值排序变成这样

NSArray*arr=@[@{@"index":@"1",@"key":@"value"},

@{@"index":@"2",@"key":@"value"},
@{@"index":@"3",@"key":@"value"},
@{@"index":@"4",@"key":@"value"}];

方法一：

-(NSComparisonResult)compare:(Person*)otherObject{
return[self.birthDatecompare:otherObject.birthDate];
}
NSArray*sortedArray;
sortedArray=[drinkDetailssortedArrayUsingSelector:@selector(compare:)];

方法二：（推荐）

NSSortDescriptor*sortDescriptor;
sortDescriptor=[[[NSSortDescriptoralloc]initWithKey:@"birthDate"
ascending:YES]autorelease];
NSArray*sortDescriptors=[NSArrayarrayWithObject:sortDescriptor];
NSArray*sortedArray;
sortedArray=[drinkDetailssortedArrayUsingDescriptors:sortDescriptors];

方法三：

NSArray*sortedArray;
sortedArray=[drinkDetailssortedArrayUsingComparator:^NSComparisonResult(ida,idb){
NSDate*first=[(Person*)abirthDate];
NSDate*second=[(Person*)bbirthDate];
return[firstcompare:second];
}];