colinfwalsh / this-button-is-epoch-ios-0616

This Button Is Epoch

1. Create a simple view that connects an IBAction to a UILabel

Introduction

What is epoch time?

The Unix epoch (or Unix time or POSIX time or Unix timestamp) is the number of seconds that have elapsed since January 1, 1970 (midnight UTC/GMT), not counting leap seconds (in ISO 8601: 1970-01-01T00:00:00Z). Literally speaking the epoch is Unix time 0 (midnight 1/1/1970), but 'epoch' is often used as a synonym for 'Unix time'. Many Unix systems store epoch dates as a signed 32-bit integer, which might cause problems on January 19, 2038 (known as the Year 2038 problem or Y2038).

-The Epoch Converter

Instructions

Open the EpochButton.xcworkspace file and navigate to the Main.storyboard file.

1. Drag on a View Controller object. Make it the initial view controller and set the simulated size metric to something familiar, such as "iPhone 4.7-inch".

2. Create a new subclass of UIViewController calledFISEpochViewController. Set the class of your view controller in the storyboard to FISEpochViewController.

3. Add a UILabel centered in the top half of the view controller's canvas, then set the accessibility label of this UILabel to epoch label and make sure the accessibility enabled box is checked. Connect this label as an outlet property on FISEpochViewController; name it something appropriate.

4. Add a UIButtoncentered in the bottom half of the view controller's canvas, then:

• set the button's title to Epoch Button!,
• set the accessibility label to epoch button and make sure the accessibility enabled box is checked, and
• connect the button's IBAction to the FISEpochViewController; name it something appropriate.

6. Write the implementation for your IBAction so that when the UIButton is tapped, the UILabel's text is updated to the result of calling the following method (which you should insert into the FISEpochViewController.m file as a helper method):

- (CGFloat)epochMethod {
    return [[NSDate date] timeIntervalSince1970];
}

Hint: If this method returns a float value, how can we display that value as a string?

If you connected this action correctly, the lab's single test should pass.

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