数组排序

NSArray *msgList = [Result objectForKey:@"msgList"];
if (msgList.count>0) {
msgList = [msgList sortedArrayUsingComparator:^NSComparisonResult(NSDictionary * obj1, NSDictionary * obj2){
return [[obj2 objectForKey:@"msgts"] compare:[obj1 objectForKey:@"msgts"]];
}];