我有下面的代码,将JSON字符串解码为一个对象数组,然后可以在UITableView中使用。优化慢代码 - 枚举字典
起初我以为JSON解码是慢的部分,但它似乎并不像“字典完成”几乎立即出现。
有关如何让代码更快一点的任何想法?
-(void)parseJSON:(NSString *)jsonData{
NSLog(@"Start parsing");
NSDictionary *deserializedData = [jsonData objectFromJSONString];
NSLog(@"Dictionary Done");
NSArray *flights = [deserializedData valueForKeyPath:@"flights.flight"];
NSMutableArray *localArray = [[NSMutableArray alloc] init ];
NSString *lastFlightno [email protected]"";
for (NSDictionary *flight in flights){
ArchiveFlight *aFlight = [[ArchiveFlight alloc] initWithFlightno:[flight objectForKey:@"flightno"] route:[flight objectForKey:@"route"]];
aFlight.flightID = [flight objectForKey:@"primary_key"];
aFlight.timeStamp = [aFlight niceDate:[flight objectForKey:@"timestamp"]];
if (![lastFlightno isEqualToString:aFlight.flightno]) {
[localArray addObject:aFlight];
}
lastFlightno =aFlight.flightno;
[aFlight release];
}
NSLog(@"End Parsing");
[self loadupTable:localArray];
self.flightArray = localArray;
[localArray release];
}
编辑:添加时间戳
时间戳如下NSLogs的...
2011-04-26 13:22:36.104 App[1778:707] Finished request
2011-04-26 13:22:36.109 App[1778:707] Start parsing
2011-04-26 13:22:36.128 App[1778:707] Dictionary Done
2011-04-26 13:22:37.713 App[1778:707] End Parsing
样品的JSON的...
{"flights":[{"flight":{"flightno":"RYR54WP","timestamp":"2011-04-26 12:13:04","route":"EGNX-LEAL","primary_key":"836453"}},{"flight":{"flightno":"RYR24LU","timestamp":"2011-04-26 09:14:03","route":"EVRA-EGNX","primary_key":"831318"}},{"flight":{"flightno":"RYR39WH","timestamp":"2011-04-26 05:33:03","route":"EGNX-EVRA","primary_key":"825492"}},{"flight":{"flightno":"RYR7PX","timestamp":"2011-04-25 20:07:03","route":"LELC-EGNX","primary_key":"816703"}},{"flight":{"flightno":"RYR2VB","timestamp":"2011-04-25 16:57:06","route":"EGNX-LELC","primary_key":"810900"}},{"flight":{"flightno":"RYR3JN","timestamp":"2011-04-25 12:36:04","route":"GCTS-EGNX","primary_key":"802631"}},{"flight":{"flightno":"RYR8GV","timestamp":"2011-04-25 06:07:03","route":"EGNX-GCTS","primary_key":"792945"}},{"flight":{"flightno":"RYR82QR","timestamp":"2011-04-24 19:42:04","route":"EPKK-EGNX","primary_key":"783306"}},{"flight":{"flightno":"RYR51PV","timestamp":"2011-04-24 16:31:05","route":"EGNX-EPKK","primary_key":"777835"}},{"flight":{"flightno":"RYR53AQ","timestamp":"2011-04-24 14:09:05","route":"LIME-EGNX","primary_key":"773572"}},{"flight":{"flightno":"RYR1CX","timestamp":"2011-04-24 11:02:05","route":"EGNX-LIME","primary_key":"768285"}},{"flight":{"flightno":"RYR9ZW","timestamp":"2011-04-24 08:21:04","route":"LEGE-EGNX","primary_key":"764624"}},{"flight":{"flightno":"RYR63BC","timestamp":"2011-04-24 05:48:02","route":"EGNX-LEGE","primary_key":"761726"}},{"flight":{"flightno":"RYR7PX","timestamp":"2011-04-23 19:39:03"
格式化样本:
{
"flights":[
{
"flight":{
"flightno":"RYR54WP",
"timestamp":"2011-04-26 12:13:04",
"route":"EGNX-LEAL",
"primary_key":"836453"
}
},
{
"flight":{
"flightno":"RYR24LU",
"timestamp":"2011-04-26 09:14:03",
"route":"EVRA-EGNX",
"primary_key":"831318"
}
}
]
}
编辑2:
因此,这里是 “niceDate”,是造成减速!
-(NSString *)niceDate:(NSString *)oldDate{
NSDateFormatter *formatter = [[[NSDateFormatter alloc] init]autorelease];
[formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSDate *sourceDate = [formatter dateFromString:oldDate];
NSDateFormatter *dateFormatter = [[[NSDateFormatter alloc] init] autorelease];
[dateFormatter setDateStyle:NSDateFormatterFullStyle];
[dateFormatter setTimeStyle:NSDateFormatterLongStyle];
NSString *timeString = [dateFormatter stringFromDate:sourceDate];
return [NSString stringWithFormat:@"%@",timeString];
}
您是否提供了一些性能分析时间戳来查看哪一部分花费最多时间? – 2011-04-26 12:16:45
增加了一些时间戳,但不能真正在循环中插入一些没有真正放慢速度的内容! – 2011-04-26 12:25:13
我们在谈论多少次迭代?你可以输入一些日志代码,只是看看你的循环在第一次10/50/100迭代中的效果如何。也许由于某种原因,性能会下降? – 2011-04-26 12:30:23