iOS 备忘录

iOS 时区：

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

    

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

    

//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    
    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
    [formatter setDateFormat:@"yyyy-MM-dd HH:mm:ss Z"];
    [formatter setTimeZone:[NSTimeZone timeZoneWithName:@"Asia/Tokyo"]];
    NSDate *time = [formatter dateFromString:@"2011-09-27 10:11:30 +0600"];
    NSLog(@"Tokyo time is %@",[formatter stringFromDate: time]);

//NSDate转NSString:
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss"];
NSString *strDate = [dateFormatter stringFromDate:[NSDate date]];
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"];