#uialertview

A UIAlertController object displays an alert message to the user. This class replaces the UIActionSheet and UIAlertView classes for displaying alerts. In this tutorial we will display an alert when the user clicks a button. This tutorial is made with Xcode 10 and built for iOS 12.

Open Xcode and create a new Single View App.

For product name, use IOSDisplayAlertTutorial and then fill out the Organization Name and Organization Identifier with your customary values. Enter Swift as Language and choose Next.

Go to the Storyboard and drag a Button to the main View. Double-click the button and give it a title of "Display Alert". Select the button and click the Pin Auto Layout button on the bottom-right of the Storyboard. Pin the button at the top edge and select "Items of New Constraints" at the Update Frames section. Select "Add 1 Constraint".

Select the button and click the Align Auto Layout button. Select the "Horizontally in Container" checkbox and select "Items of New Constraints" at the Update Frames section. Select "Add 1 Constraint".

Select the Assistant Editor and open ViewController.swift. Ctrl-drag or right-click-drag from the Button to the class and create the following Action.

Next, implement the showAlert function.

@IBAction func showAlert(_ sender: Any) { let alertController = UIAlertController(title: "iOScreator", message: "Hello, world!", preferredStyle: .alert) alertController.addAction(UIAlertAction(title: "Dismiss", style: .default)) self.present(alertController, animated: true, completion: nil) }

The alertController constant is assigned an UIAlertController object. Since we will show an Alert the preferredStyle is set to alert. The alertController is then presented modally with the present(_:animated:completion:) method. Build and Run the project and press the Display Alert button to display the alert.

UIAlertController: Alert and Action Sheet in iOS

In this tutorial, I will show you the new way to display an alert message to the user and associate user actions with that alert message in your iOS app.

UIAlertView and UIActionSheet, introduced in iOS 2, were deprecated in iOS 8. And now, starting from iOS 8, they have both been replaced by UIAlertController. But for apps that target prior versions of iOS 8, you should still use the UIAlertView class to display an alert message to the user and the UIActionSheet class to present the user with a set of alternatives for how to proceed with a given task. Action sheets are also used to prompt the user to confirm a potentially dangerous action (for example, to request the user to confirm to delete a file). If you need to show alerts in apps before iOS 8, you should read our iPhone user alerts post. We have recently updated this post by adding Objective-C and Swift side by side.

Fixed: Create UIActionSheet 'otherButtons' by passing in array, not varlist #dev #fix #it

Create UIActionSheet ‘otherButtons’ by passing in array, not varlist

I have an array of strings that I want to use for button titles on a UIActionSheet. Unfortunately, the otherButtonTitles: argument in the method invocation takes a variable length list of strings, not an array.

So how I can I pass these titles into the UIActionSheet? The workaround I’ve seen suggested is to pass nil into…

The UIKeyInput protocol defines a -(BOOL)hasText method. Typically you would call this on a UITextView or UITextField to determine if the receiver has text in it.

Consider this example:

UITextField *textField = [[UITextField alloc] init]; [self.view addSubview:textField]; NSLog(@"%i", [textField hasText]); [textField setText:@"Letter"]; NSLog(@"%i", [textField hasText]); [textField becomeFirstResponder]; dispatch_async(dispatch_get_main_queue(), ^{ NSLog(@"%i", [textField hasText]); });

You would think the output from those NSLogs would be:

0 1 1

Wrong. The actually print out is:

0 6 1

Apparently, when the object conforming to UIKeyInput is not the first responder, hasText returns the length of the string.

Normally this wouldn't cause anyone any problems. For instance in this condition:

if ([textField hasText]) { NSLog(@"Great!"); }

Everything here will be fine. The length of the string in this case is essentially equivalent to if hasText were to always return a BOOL instead of the length.

However, if someone were to write:

if ([textField hasText] == YES) { NSLog(@"Not Great :("); }

That would not be fine if the text field were not the first responder. 6 == YES would be false, and nothing would print to the console.

Here comes the insidious bug.

-(BOOL)alertViewShouldEnableFirstOtherButton:(UIAlertView *)alertView

If you return [textField hasText] from this UIAlertViewDelegate method, you will be making a mistake. Without knowledge of the internals of this UIKit method, it appears that it is making an == YES check on the value you provide. You can read about why that would be a bad idea over at the Big Nerd Ranch.

This can cause the button to be disabled if the text field you are checking is not the first responder, and it has an even number of characters.

While upgrading Meep to iOS 7 it became necessary to reimplement the standard UIAlertView provided by Apple because we wanted to specify a custom UIView underneath the title (an image) and also change the styling from the default colours.

Previously we were subclassing UIAlertView and overriding the drawRect method to differentiate from the default look and feel, but this was dangerous as Apple even mentioned in their docs that subclassing of UIAlertView was not supported.

PXAlertView now mimics the iOS 7 UIAlertView in every way but has a default dark style and an easier block based syntax for the API.

Released under the permissive MIT licence, you can do with it as you please, it makes a great alternative to the default UIAlertView and you have the power to customise it to your hearts content.

In my current project I had to change flow of "success and error blocks" in API calls, and add "retry block" in order to be able to retry every failed connection. It turned out to be not so trivial task in current architecture, but I've managed to do it with using alert views with blocks (it's not so interesting how at the moment). At first I've used some library that supported blocks, but also changed completely alert view pattern

http://i.imgur.com/3s3eJ.png

We did like it, but client decided it's too different from default, so I needed to changed it. At first I've looked for solutions with default Alert View, but didn't find anything good enough. So I've decided to create my own UIAlertView category that supports block in about 20 lines of code:

#import <UIKit/UIKit.h> typedef void(^UIAlertViewActionBlock)(void); @interface UIAlertView (Blocks) - (void)addBlock:(UIAlertViewActionBlock)block; - (void)addBlock:(UIAlertViewActionBlock)block forButtonIndex:(NSInteger)index; @end

#import "UIAlertView+Blocks.h" #import <objc/runtime.h> @implementation UIAlertView (Blocks) static NSString *handlersDictionaryKey = @"handlersDictionaryKey"; - (void)addBlock:(UIAlertViewActionBlock)block { [self addBlock:block forButtonIndex:self.firstOtherButtonIndex]; } - (void)addBlock:(UIAlertViewActionBlock)block forButtonIndex:(NSInteger)index { NSMutableDictionary *handlersDictionary = objc_getAssociatedObject(self, (__bridge void *)handlersDictionaryKey); if (handlersDictionary == nil) { handlersDictionary = [NSMutableDictionary dictionary]; } handlersDictionary[@(index)] = block; objc_setAssociatedObject(self, (__bridge void *)handlersDictionaryKey, handlersDictionary, OBJC_ASSOCIATION_RETAIN_NONATOMIC); self.delegate = self; } #pragma mark - UIAlertViewDelegate - (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex { NSMutableDictionary *handlersDictionary = objc_getAssociatedObject(self, (__bridge void *)handlersDictionaryKey); if (handlersDictionary) { UIAlertViewActionBlock handler = handlersDictionary[@(buttonIndex)]; if (handler) { handler(); } } } @end