iOS 备忘录

iOS 时区：

1 //先是将指定时区的日期转换为当前时区时间:   
2     NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
3     [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss Z"];
4     [formatter setTimeZone:[NSTimeZone defaultTimeZone] ] ;
5     NSDate *time = [formatter dateFromString:@"2011-09-27 10:11:30 +0600"];    
6     NSLog(@"Local time is %@",[formatter stringFromDate: time]);

1 //然后是将当前时区时间转换为特定时区的:
2     NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
3     [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss Z"];
4     [formatter setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Tokyo"]];
5     NSLog(@"Now Tokyo time is %@",[formatter stringFromDate:[NSDate date]]);

1 //下面是将指定时区的某个日期时间转化为指定时区的时间    
2     NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
3     [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss Z"];
4     [formatter setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Tokyo"]];
5     NSDate *time = [formatter dateFromString:@"2011-09-27 10:11:30 +0600"];
6     NSLog(@"Tokyo time is %@",[formatter stringFromDate: time]);

1 //NSDate转NSString:
2 NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
3 [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
4 NSString *strDate = [dateFormatter stringFromDate:[NSDate date]];
5 NSLog(@"%@", strDate);

iOS 语法糖

NSNumber 可以用@数字来构造，如@3或者@（3）；

NSArray 可以用@[]构造，如@[v1,v2,v3]；

NSDictionary可以用@{}构造，如@{k1:v1,k2:v2};

iOS版本号获取

NSString *currentVersion = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"CFBundleShortVersionString"];