NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"hh:mm:ss a"];
NSLog(@"Current Date: %@", [formatter stringFromDate:[NSDate date]]);
[formatter release];
setDateFormat中字符串的格式基于ISO-8601http://en.wikipedia.org/wiki/ISO_8601#Dates
Swift 3版本:
let formatter = DateFormatter()
formatter.dateFormat = "hh:mm:ss a"
print("Current date: \(formatter.string(from: Date()))") // -> Current date: 08:48:48 PM
还有一个新的网站，因为这个原始的答案，帮助编写这些格式字符串.恰如其分的名字...http://nsdateformatter.com