Get full string in iOS8 Custom Keyboard Extension

问题:

I'm creating a Custom Keyboard Extension for iOS 8.

I want to get the whole string that the user wrote in the text input field.

Unfortunately I stumble in to two main problems:

1) I get null in this callback:

- (void)textDidChange:(id<UITextInput>)textInput

2) I only get partial String When I call these methods:

- [self.textDocumentProxy documentContextAfterInput];
- [self.textDocumentProxy documentContextBeforeInput];

I want to get the whole string in the text input the user is currently editing what do you suggest i do?

Thanks!

回答1:

I found How To.

- (void)doSomething{
    dispatch_async(inputQueue, ^{
        [self getAllString];
    });
    return;
}

First Wrap Your Method With dispatch_async and your own queue.

#define DELAY_LENGTH 0.01

-(void)getAllString{
    id<UITextDocumentProxy> proxy = self.textDocumentProxy;
    NSString* before = [proxy documentContextBeforeInput];
    NSString* after = [proxy documentContextAfterInput];

    NSMutableArray* afterArray = [NSMutableArray arrayWithCapacity:10];

    while (after) {
        unsigned long afterLength = [after length];
        if(afterLength <= 0){
            break;
        }
        [afterArray addObject:after];
        [NSThread sleepForTimeInterval:DELAY_LENGTH];
        [proxy adjustTextPositionByCharacterOffset:afterLength];
        [NSThread sleepForTimeInterval:DELAY_LENGTH];
        after = [proxy documentContextAfterInput];
    }

    NSMutableArray* beforeArray = [NSMutableArray arrayWithCapacity:10];

    [NSThread sleepForTimeInterval:DELAY_LENGTH];
    before = [proxy documentContextBeforeInput];

    while (before) {
        unsigned long beforeLength = [before length];
        if (beforeLength <= 0) {
            break;
        }
        [beforeArray addObject:before];
        [NSThread sleepForTimeInterval:DELAY_LENGTH];
        [proxy adjustTextPositionByCharacterOffset:-beforeLength];
        [NSThread sleepForTimeInterval:DELAY_LENGTH];
        before = [proxy documentContextBeforeInput];
    }

    NSLog(@"afterArray: %@",[self getArrayString:afterArray reverse:false]);

    NSString* beforeString = [self getArrayString:beforeArray reverse:true];

    NSLog(@"beforArray: %@",beforeString);

    [NSThread sleepForTimeInterval:DELAY_LENGTH];
    [proxy adjustTextPositionByCharacterOffset:beforeString.length];
}

There are two utils :

@implementation NSArray (Reverse)

- (NSArray *)reversedArray {
    NSMutableArray *array = [NSMutableArray arrayWithCapacity:[self count]];
    NSEnumerator *enumerator = [self reverseObjectEnumerator];
    for (id element in enumerator) {
        [array addObject:element];
    }
    return array;
}

@end

and

-(NSString*)getArrayString : (NSArray*)array
                   reverse : (BOOL)isReverse{
    NSArray* tar = isReverse ? [array reversedArray] : array;
    NSMutableString* result = [NSMutableString stringWithCapacity:10];
    for (NSString* string in tar) {
        [result appendString:string];
    }
    return result;
}

YOU HAVE TO SLEEP LITTLE FOR EACH PROXY METHOD.

result :

TextBox

012, 345! 6789
0123. 4567! 89012 '34567890.' 123456789

Console

2015-03-18 21:04:15.034 moveCursor[39413:2692914] afterArray: 
2015-03-18 21:04:15.035 moveCursor[39413:2692914] beforArray: 012, 345! 6789
0123. 4567! 89012 '34567890.' 123456789

回答2:

I ran into the same problem with the documentContextAfterInput and documentContextBeforeInput strings. I think that IOS8 only returns a handful of characters on either side of the insertion point. I think this is intentional.

回答3:

You could always have a mutable array you store all typed text in, and remove the last character when deleting(or maybe do some detection with documentContextAfterInput/BeforeInput to find the spot to delete text, then remove that portion). This is more complicated than just calling a 'giveMeWholeString' method, but it would work for most cases, especially if they were only typing and deleting with the delete key.

回答4:

I had the same problem and I think it has been fixed with Xcode 6 beta 4.

Just append documentContextAfterInput to documentContextBeforeInput to get the full input field text.

回答5:

in Xcode 6.1 it seems that documentContextBeforeInput returns partial string only in simulator and works fine on the device.

Edit: ok guys here's my code:

-(void)addPeriod{
if (![self endsWithCharacter:'.' String:[[((UIInputViewController*)self.delegate).textDocumentProxy documentContextBeforeInput] stringByReplacingOccurrencesOfString:@" " withString:@""]]) {
    [((UIInputViewController*)self.delegate).textDocumentProxy deleteBackward];
    [((UIInputViewController*)self.delegate).textDocumentProxy insertText:@"."];
}
}
- (BOOL) endsWithCharacter: (unichar) c String:(NSString*)str
{
    NSLog(@"%@",str);
    NSUInteger length = [str length];
    return (length > 0) && ([str characterAtIndex: length - 1] == c);
}

and the output (on the device only) is: 2014-11-16 12:32:42.708 Keyboard[2228:393159] Thanks!howareyou?