NSSortDescriptor

NSSortDescriptor 指定用于对象数组排序的对象的属性。

NSMutableArray *ma1 =[[NSMutableArray alloc] init];
[ma1 addObject:@"2"];
[ma1 addObject:@"1"];
[ma1 addObject:@"3"];

NSSortDescriptor *sd1 = [NSSortDescriptorsortDescriptorWithKey:@"self" ascending:NO];
NSArray *arr1 = [ma1 sortedArrayUsingDescriptors:[NSArray arrayWithObjects:sd1,nil]];

for (NSString *str in arr1) {
NSLog(@"%@", str);
}

NSMutableArray *ma2 = [[NSMutableArray alloc] init];
[ma2 addObject:@"b"];
[ma2 addObject:@"c"];
[ma2 addObject:@"a"];

NSSortDescriptor *sd2 = [NSSortDescriptorsortDescriptorWithKey:@"self" ascending:YES];
NSArray *arr2 = [ma2 sortedArrayUsingDescriptors:[NSArray arrayWithObjects:sd2,nil]];

for (NSString *str in arr2) {
NSLog(@"%@", str);
}

NSMutableArray *ma3 = [[NSMutableArray alloc] init];

NSMutableDictionary *md1 = [[NSMutableDictionary alloc] init];
[md1 setObject:@"e" forKey:@"name"];

NSMutableDictionary *md2 = [[NSMutableDictionary alloc] init];
[md2 setObject:@"d" forKey:@"name"];

NSMutableDictionary *md3 = [[NSMutableDictionary alloc] init];
[md3 setObject:@"f" forKey:@"name"];

[ma3 addObject:md1];
[ma3 addObject:md2];
[ma3 addObject:md3];

[md1 release];
[md2 release];
[md3 release];

NSSortDescriptor *sd3 = [NSSortDescriptorsortDescriptorWithKey:@"name" ascending:YES];
NSArray *arr3 = [ma3 sortedArrayUsingDescriptors:[NSArray arrayWithObjects:sd3,nil]];

for (NSMutableDictionary *md in arr3) {
NSLog(@"%@", [md objectForKey:@"name"]);
}

[ma1 release];
[ma2 release];
[ma3 release];

转自：http://www.cnblogs.com/zhw511006/archive/2011/06/16/2082787.html

NSSortDescriptor 指定用于对象数组排序的对象的属性。

如果是Employee对象需要按照name来排序，就生成下面的descriptor

NSSortDescriptor *descriptor = [NSSortDescriptor sortDescriptorWithKey:name ascending:YES];

如果需要多个排序，比如先按name排序，再按入职日期排序。那就创建两个descriptor

NSSortDescriptor *descriptor = [NSSortDescriptor sortDescriptorWithKey:hireDate ascending:YES];

两个descriptor放到数组里一起传给需要排序的数组。

如果对象就是NSString，就是字符串数组排序，那更简单了，sortdescriptor的key直接指定为nil，就直接排序对象，而不是对象的某一个属性了。

NSSortDescriptor *descriptor= [NSSortDescriptor sortDescriptorWithKey:nil ascending:YES];

NSArray *descriptors= [NSArray arrayWithObject:descriptor];

NSArray *myDataArray=[NSArray arrayWithObjects:@"what", @"xero", @"highligth", @"mountain",@"Victory", @"Balance", nil];

NSArray *resultArray= [myDataArray sortedArrayUsingDescriptors:descriptors];

NSLog(@"%@",resultArray);

NSArray 使用sortedArrayUsingDescriptors，返回排序好的数组。

NSMutableArray可以直接使用sortUsingDescriptors，对数组本身排序。

转自：http://blog.sina.com.cn/s/blog_8c87ba3b0101phr5.html