I am using NSDateFormatter in my project using Swift language.
I am getting following error:
Variable 'dateFormatter' used before being initialized
My code:
var date : NSDate = (NSDate.date())
var dateFormatter : NSDateFormatter
dateFormatter.dateFormat = "dd:mm:yyyy HH:mm:ss zzz"
Change just one line.
You not initialise the NSDateFormatter
change below line:
var dateFormatter : NSDateFormatter = NSDateFormatter()
Complete code:
var date : NSDate = (NSDate.date())
var dateFormatter : NSDateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "dd:mm:yyyy HH:mm:ss zzz"
New usage would be:
let date = Date()
let formatter = DateFormatter()
formatter.dateFormat = "MM.dd.yy" // or whatever format
let dateStr = formatter.string(from: date)
First you need to initialise, then you won't get error.
In Swift, initilization completes with ().
var dateFormatter = NSDateFormatter()
Related
How do I convert the following Objective-C code into Swift code?
#define MAX_SIZE 11
char buffer[MAX_SIZE];
time_t time = [[NSDate date] timeIntervalSince1970];
strftime(buffer, MAX_SIZE, "%-l:%M\u2008%p", localtime(&time));
NSString *dateString = [NSString stringWithUTF8String:buffer];
NSLog(#"dateString: %#", dateString); // dateString: 11:56 PM
I'm formatting a date.
As the commentators #BryanChen and #JasonCoco said, use NSDateFormatter.
let dateFormatter = NSDateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd 'at' h:mm a" // superset of OP's format
let str = dateFormatter.stringFromDate(NSDate())
A full description of the format strings is available in "Data Formatting Guide".
Here is another example that uses NSDateFormatterStyle:
private func FormatDate(date:NSDate) -> String {
let dateFormatter = NSDateFormatter()
dateFormatter.dateStyle = NSDateFormatterStyle.LongStyle
return dateFormatter.stringFromDate(date)
}
The output is formatted as, "January 1, 1990".
If you want to read more about the formatter and the different available styles, checkout, NSFormatter under NSDateFormatter section.
My function i use.
extension NSDate {
public func toString (format: String) -> String {
let formatter = NSDateFormatter ()
formatter.locale = NSLocale.currentLocale()
formatter.dateFormat = format
return formatter.stringFromDate(self)
}
}
date.toString("yyyy-MM-dd")
let maxSize: UInt = 11
var buffer: CChar[] = CChar[](count: Int(maxSize), repeatedValue: 0)
var time: time_t = Int(NSDate().timeIntervalSince1970)
var length = strftime(&buffer, maxSize, "%-l:%M\u2008%p", localtime(&time))
var dateString = NSString(bytes: buffer, length: Int(length), encoding: NSUTF8StringEncoding)
NSLog("dateString: %#", dateString) // dateString: 11:56 PM
if I try:
NSDateFormatter* formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyyMMdd"];
and
[formatter dateFromString:#"20120423"];
My new NSDate object will be: 2012 04 22. Why one day less?
Thank
You have problems with time zone and it can be solved by adding this line of code:
formatter.timeZone = [NSTimeZone timeZoneWithName:#"GMT"];
For those who looks for swift 3 version
let formatter = DateFormatter()
formatter.timezone = TimeZone(abbreviation: "GMT")
formatter.dateFormat = "yyyyMMdd"
formatter.date(from: "20120423")
For one liners using Swift 3
Date.init(dateString: "2014-07-31", format: "yyyy-MM-dd", timeZone: TimeZone.init(abbreviation: "GMT")!)
First of all I want to say thanks in advance for helping me.
I want to know how can I create a date on a label using Xcode,
and the date will follow the same date like in iphone.
Thanks
Here's one simple approach
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
//uncomment to get the time only
//[formatter setDateFormat:#"hh:mm a"];
//[formatter setDateFormat:#"MMM dd, YYYY"];
[formatter setDateStyle:NSDateFormatterMediumStyle];
//get the date today
NSString *dateToday = [formatter stringFromDate:[NSDate date]];
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 320.0f, 20.0f)];
[label setText:dateToday];
[formatter release];
//then add to a view
Creating the text date is simple, but the real question is what is your data source that you want to make the date text out of?
The date can be formatted and set in label as below.
NSDate *today = [NSDate date];
NSDateFormatter *dformat = [[NSDateFormatter alloc] init];
[dformat setDateFormat:#"dd:MM:YYYY"];
myLabel.text = [dformat stringFromDate:today];
NSDateFormatter handle format of string dates.
Instances of NSDateFormatter create string representations of NSDate objects, and convert textual representations of dates and times into NSDate objects.
Try this and see:
// Set date format according to your string date format
// e.g.: For,
// 22-12-1996 -> #"dd-MM-yyyy"
// 22/12/1996 -> #"dd/MM/yyyy"
// 1996-12-22 03:45:20 -> #"yyyy-MM-dd HH:mm:ss"
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.dateFormat = #"dd/MM/yyyy";
//dateFormatter.dateFormat = #"dd-MM-yyyy";
NSDate *date = [dateFormatter dateFromString:dateString];
if(date == nil) {
correctFormat = false;
}
NSLog("Date: %#",date);
Note: Each pairs of characters in date format relates relevant date component with date instance. You can create any type of date format using date string pattern.
Here is document by Apple: Date Formatters
Date (Day): dd
Month: MM or MMM or MMMM
Year: yy or yyyy
Here is list of date formats: Date Formats
Here is solution in Swift
var today = Date()
var d_format = DateFormatter()
d_format.dateFormat = "dd:MM:yyyy"
label.text = dformat.string(from: today)
How do I get current year as string in Obj-C ?
Also how do I compare the same using another year value ?
Is it advisable to do a string comparision OR dirctly year-to-year comparision ?
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy"];
NSString *yearString = [formatter stringFromDate:[NSDate date]];
// Swift
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy"
let year = dateFormatter.string(from: Date())
You can compare NSStrings via the -isEqualToString: method.
NSCalendar *gregorian = [NSCalendar calendarWithIdentifier:NSCalendarIdentifierGregorian];
NSInteger year = [gregorian component:NSCalendarUnitYear fromDate:NSDate.date];
Note: there are several calendar identifiers besides NSGregorianCalendar. Use whatever is appropriate for your locale. You can ask for whatever set of components you'd like by bitwise OR'ing the fields together (e.g., NSYearCalendarUnit | NSMonthCalendarUnit) and using components:fromDate instead. You can read about it in the Date and Time Programming Guide.
With calendar components as primitive types, comparisons are efficient.
In Swift you can get only year by given code
let formatter = NSDateFormatter()
formatter.dateFormat = "yyyy"
let dateStr = formatter.stringFromDate(NSDate())
print(dateStr)
Output:
2017
you can get by following code in objective c
NSDateComponents *components = [[NSCalendar currentCalendar] components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear fromDate:[NSDate date]];
int year = [components year];
NSString *strFromyear = [NSString stringWithFormat:#"%d",year];
Swift
Easier way to get any elements of date as an optional String.
extension Date {
// Year
var currentYear: String? {
return getDateComponent(dateFormat: "yy")
//return getDateComponent(dateFormat: "yyyy")
}
func getDateComponent(dateFormat: String) -> String? {
let format = DateFormatter()
format.dateFormat = dateFormat
return format.string(from: self)
}
}
print("-- \(Date().currentYear)") // result -- Optional("2017")
How do I convert, NSDate to NSString so that only the year in #"yyyy" format is output to the string?
How about...
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"yyyy"];
//Optionally for time zone conversions
[formatter setTimeZone:[NSTimeZone timeZoneWithName:#"..."]];
NSString *stringFromDate = [formatter stringFromDate:myNSDateInstance];
//unless ARC is active
[formatter release];
Swift 4.2 :
func stringFromDate(_ date: Date) -> String {
let formatter = DateFormatter()
formatter.dateFormat = "dd MMM yyyy HH:mm" //yyyy
return formatter.string(from: date)
}
I don't know how we all missed this: localizedStringFromDate:dateStyle:timeStyle:
NSString *dateString = [NSDateFormatter localizedStringFromDate:[NSDate date]
dateStyle:NSDateFormatterShortStyle
timeStyle:NSDateFormatterFullStyle];
NSLog(#"%#",dateString);
outputs '13/06/12 00:22:39 GMT+03:00'
Hope to add more value by providing the normal formatter including the year, month and day with the time.
You can use this formatter for more than just a year
[dateFormat setDateFormat: #"yyyy-MM-dd HH:mm:ss zzz"];
there are a number of NSDate helpers on the web, I tend to use:
https://github.com/billymeltdown/nsdate-helper/
Readme extract below:
NSString *displayString = [NSDate stringForDisplayFromDate:date];
This produces the following kinds of output:
‘3:42 AM’ – if the date is after midnight today
‘Tuesday’ – if the date is within the last seven days
‘Mar 1’ – if the date is within the current calendar year
‘Mar 1, 2008’ – else ;-)
In Swift:
var formatter = NSDateFormatter()
formatter.dateFormat = "yyyy"
var dateString = formatter.stringFromDate(YourNSDateInstanceHERE)
NSDateFormatter *dateformate=[[NSDateFormatter alloc]init];
[dateformate setDateFormat:#"yyyy"]; // Date formater
NSString *date = [dateformate stringFromDate:[NSDate date]]; // Convert date to string
NSLog(#"date :%#",date);
If you don't have NSDate -descriptionWithCalendarFormat:timeZone:locale: available (I don't believe iPhone/Cocoa Touch includes this) you may need to use strftime and monkey around with some C-style strings. You can get the UNIX timestamp from an NSDate using NSDate -timeIntervalSince1970.
+(NSString*)date2str:(NSDate*)myNSDateInstance onlyDate:(BOOL)onlyDate{
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
if (onlyDate) {
[formatter setDateFormat:#"yyyy-MM-dd"];
}else{
[formatter setDateFormat: #"yyyy-MM-dd HH:mm:ss"];
}
//Optionally for time zone conversions
// [formatter setTimeZone:[NSTimeZone timeZoneWithName:#"..."]];
NSString *stringFromDate = [formatter stringFromDate:myNSDateInstance];
return stringFromDate;
}
+(NSDate*)str2date:(NSString*)dateStr{
if ([dateStr isKindOfClass:[NSDate class]]) {
return (NSDate*)dateStr;
}
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:#"yyyy-MM-dd"];
NSDate *date = [dateFormat dateFromString:dateStr];
return date;
}
Just add this extension:
extension NSDate {
var stringValue: String {
let formatter = NSDateFormatter()
formatter.dateFormat = "yourDateFormat"
return formatter.stringFromDate(self)
}
}
If you are on Mac OS X you can write:
NSString* s = [[NSDate date] descriptionWithCalendarFormat:#"%Y_%m_%d_%H_%M_%S" timeZone:nil locale:nil];
However this is not available on iOS.
It's swift format :
func dateFormatterWithCalendar(calndarIdentifier: Calendar.Identifier, dateFormat: String) -> DateFormatter {
let formatter = DateFormatter()
formatter.calendar = Calendar(identifier: calndarIdentifier)
formatter.dateFormat = dateFormat
return formatter
}
//Usage
let date = Date()
let fotmatter = dateFormatterWithCalendar(calndarIdentifier: .gregorian, dateFormat: "yyyy")
let dateString = fotmatter.string(from: date)
print(dateString) //2018
swift 4 answer
static let dateformat: String = "yyyy-MM-dd'T'HH:mm:ss"
public static func stringTodate(strDate : String) -> Date
{
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = dateformat
let date = dateFormatter.date(from: strDate)
return date!
}
public static func dateToString(inputdate : Date) -> String
{
let dateFormatter = DateFormatter()
dateFormatter.dateFormat = dateformat
return formatter.string(from: inputdate)
}
Use extension to have clear code
You can write an extension to convert any Date object to any desired calendar and any format
extension Date{
func asString(format: String = "yy/MM/dd HH:mm",
for identifier: Calendar.Identifier = .persian) -> String {
let formatter = DateFormatter()
formatter.calendar = Calendar(identifier: identifier)
formatter.dateFormat = format
return formatter.string(from: self)
}
}
Then use it like this:
let now = Date()
print(now.asString()) // prints -> 00/04/18 20:25
print(now.asString(format: "yyyy/MM/dd")) // prints -> 1400/04/18
print(now.asString(format: "MM/dd", for: .gregorian)) // prints -> 07/09
To learn how to specify your desired format string take a look at this link.
For a complete reference on how to format dates see Apple's official Date Formatting Guide here.
Simple way to use C# styled way to convert Date to String.
usage:
let a = time.asString()
// 1990-03-25
let b = time.asString("MM ∕ dd ∕ yyyy, hh꞉mm a")
// 03 / 25 / 1990, 10:33 PM
extensions:
extension Date {
func asString(_ template: String? = nil) -> String {
if let template = template {
let df = DateFormatter.with(template: template)
return df.string(from: self)
}
else {
return globalDateFormatter.string(from: self)
}
}
}
// Here you can set default template for DateFormatter
public let globalDateFormatter: DateFormatter = DateFormatter.with(template: "y-M-d")
public extension DateFormatter {
static func with(template: String ) -> DateFormatter {
let df = DateFormatter()
df.dateFormat = template
return df
}
}
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *components = [calendar components:(NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay) fromDate:myNSDateInstance];
NSInteger year = [components year];
// NSInteger month = [components month];
NSString *yearStr = [NSString stringWithFormat:#"%ld", year];
Define your own utility for format your date required date format
for eg.
NSString * stringFromDate(NSDate *date)
{ NSDateFormatter *formatter
[[NSDateFormatter alloc] init];
[formatter setDateFormat:#"MM ∕ dd ∕ yyyy, hh꞉mm a"];
return [formatter stringFromDate:date];
}
#ios #swift #convertDateinString
Simply just do like this to "convert date into string" as per format you passed:
let formatter = DateFormatter()
formatter.dateFormat = "dd-MM-YYYY" // pass formate here
let myString = formatter.string(from: date) // this will convert Date in String
Note: You can specify different formats such like "yyyy-MM-dd", "yyyy", "MM" etc...
Update for iOS 15
iOS 15 now supports calling .formatted on Date objects directly without an explicit DateFormatter.
Example for common formats
Documentation
date.formatted() // 6/8/2021, 7:30 PM
date.formatted(date: .omitted, time: .complete) // 19:30
date.formatted(date: .omitted, time: .standard) // 07:30 PM
date.formatted(date: .omitted, time: .shortened) // 7:30 PM
date.formatted(date: .omitted, time: .omitted)
Alternative syntax
Documentation
// We can also specify each DateComponent separately by chaining modifiers.
date.formatted(.dateTime.weekday(.wide).day().month().hour().minute())
// Tuesday, Jun 8, 7:30 pm
// Answer to specific question
date.formatted(.dateTime.year())
for Objective-C:
NSDate *date = [NSDate dateWithTimeIntervalSinceNow:0];
NSDateFormatter *formatter = [NSDateFormatter new];
formatter.dateFormat = #"yyyy";
NSString *dateString = [formatter stringFromDate:date];
for Swift:
let now = Date()
let formatter = DateFormatter()
formatter.dateFormat = "yyyy"
let dateString = formatter.string(from: now)
That's a good website for nsdateformatter.You can preview date strings with different DateFormatter in different local.