Super slow lag/delay on initial keyboard animation of UITextField
Objective CIosCocoa TouchKeyboardUitextfieldObjective C Problem Overview
Alright, this problem has been driving me nuts.
It takes roughly 3-4 seconds for the keyboard to pop up after I touch my UITextField. This only occurs on the first time the keyboard pops up since the app launched, afterwards the animation starts instantly.
At first I thought it was problem of loading too many images, or my UITableView, but I just created a brand new project with only a UITextField, and I still experience this problem. I'm using iOS 5, Xcode ver 4.2, and running on an iPhone 4S.
This is my code:
#import "ViewController.h"
@implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
UITextField *textField = [[UITextField alloc] initWithFrame:CGRectMake(20, 20, 280, 30)];
textField.borderStyle = UITextBorderStyleRoundedRect;
textField.delegate = self;
[self.view addSubview:textField];
}
@end
Is this a common problem for all apps?
Right now, the only way I can make it somewhat better is by having textField become/resign first responder in viewDidAppear, but that doesn't solve the problem entirely - it just loads the delay onto when the view loads instead. If I click on textField immediately when the view loads, I still get the problem; if I wait 3-4 seconds after the view loads before touching the textField, I don't get the delay.
Objective C Solutions
Solution 1 - Objective C
Before you implement any exotic hacks to get around this problem, try this: stop the debug session, close the app from multitasking, unplug your device from the computer and run the app normally by tapping its icon. I have seen at least two cases in which the delay only occurs while the device is plugged in.
Solution 2 - Objective C
So the problem is NOT just limited to the first install as I had previously thought, but happens every time the app is launched. Here's my solution that solves the issue completely.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// Preloads keyboard so there's no lag on initial keyboard appearance.
UITextField *lagFreeField = [[UITextField alloc] init];
[self.window addSubview:lagFreeField];
[lagFreeField becomeFirstResponder];
[lagFreeField resignFirstResponder];
[lagFreeField removeFromSuperview];
}
Solution 3 - Objective C
Yeah, I also got a few seconds delay on the latest iPhone 4s. Don't panic. For some reasons, it only happens the first time the app is loaded from Xcode in Debug. When I did Release, I don't get the delay. Just forget it...
Solution 4 - Objective C
This is a known issue.
Preloading keyboard seems promising. Check Preloading the UIKeyboard.
Some additional reading material:
https://stackoverflow.com/questions/8862659/uitextfield-keyboard-blocks-runloop-while-loading
Solution 5 - Objective C
You can use Vadoff's solution in Swift by adding this to didFinishLaunchingWithOptions:
// Preloads keyboard so there's no lag on initial keyboard appearance.
let lagFreeField: UITextField = UITextField()
self.window?.addSubview(lagFreeField)
lagFreeField.becomeFirstResponder()
lagFreeField.resignFirstResponder()
lagFreeField.removeFromSuperview()
It is working for me in iOS 8.
Solution 6 - Objective C
Code in block added to main queue and run asynchronously. (don't locked main thread)
dispatch_async(dispatch_get_main_queue(), ^(void){
[textField becomeFirstResponder];
});
Solution 7 - Objective C
See this answer. They suggest UIResponder+KeyboardCache. It's simple and awesome. Tested on iOS 7.
Solution 8 - Objective C
A related problem, where a UIViewController would be slow to present, was solved by using the system font instead of a custom font on the UITextField. Perhaps using the system font might also work for this problem?
Solution 9 - Objective C
This bug seems to be fixed in iOS 9.2.1. Since upgrading my device, I no longer have a delay between tapping a text field and the keyboard appearing when my device is connected to my computer.
Solution 10 - Objective C
This selected answer causes BAD_EXC crash on iOS 11 - remove from app to fix
Solution 11 - Objective C
You can add below code when viewController's view did loaded, like viewDidAppear.Not just application:didFinishLaunchingWithOptions:
UITextField *lagFreeField = [[UITextField alloc] init];
[self.window addSubview:lagFreeField];
[lagFreeField becomeFirstResponder];
[lagFreeField resignFirstResponder];
[lagFreeField removeFromSuperview];