如何从iphone中的uitextfield中选择文本？ [英] how to get selected text from uitextfield in iphone?

问题描述

我正在研究iPhone中的文本到语音应用程序，

I am working on Text to speech application in iPhone,

其中有一个文本字段需要输入，我希望用户从文本中选择部分文本字段和我的应用程序会将所选文本转换为语音。

in which have a text field that takes input, i want user to select some portion of text from text field and my application will convert that selected text into speech.

我的问题是如何获取用户从文本字段中选择的文本？

my problem is how would i get the text that user has selected from text field?

推荐答案

- [UITextField selectedText]

虽然 UITextField 没有 selectedText 方法，它符合 UITextInput protocol 。因此，您可以使用所需的属性和 UITextInput 协议的方法，用于确定 UITextField * textField selectedText $ c>（或任何符合 UITextInput 协议的对象，例如 UITextView ）。

-[UITextField selectedText]

Although UITextField doesn't have a selectedText method, it conforms to the UITextInput protocol. So, you can use the required properties & methods of the UITextInput protocol to determine the selectedText of a UITextField *textField (or any object that conforms to the UITextInput protocol, such as a UITextView).

NSString *selectedText = [textField textInRange:textField.selectedTextRange];
NSLog(@"selectedText: %@", selectedText);

除此之外，您还可以使用所需的属性& UITextInput 的方法来计算 UITextField * textField selectedRange c>。

As an aside, you can also use the required properties & methods of the UITextInput to calculate the selectedRange of a UITextField *textField.

UITextRange *selectedTextRange = textField.selectedTextRange;
NSUInteger location = [textField offsetFromPosition:textField.beginningOfDocument
                                         toPosition:selectedTextRange.start];
NSUInteger length = [textField offsetFromPosition:selectedTextRange.start
                                       toPosition:selectedTextRange.end];
NSRange selectedRange = NSMakeRange(location, length);
NSLog(@"selectedRange: %@", NSStringFromRange(selectedRange));

- [UITextFieldDelegate textFieldDidChangeSelection：]

虽然， UITextFieldDelegate 未声明 textFieldDidChangeSelection：委托像这样的方法在 UITextField 的选择发生变化。为此，子类 UITextField 并使用方法swizzling将自己的代码添加到 textField.inputDelegate 的本机实现中 - [UITextInputDelegate selectionDidChange：] 。

-[UITextFieldDelegate textFieldDidChangeSelection:]

Although, UITextFieldDelegate doesn't declare a textFieldDidChangeSelection: delegate method like -[UITextViewDelegate textViewDidChangeSelection:], you can still hook into when the selection of a UITextField has changed. To do so, subclass UITextField and use method swizzling to add your own code to the textField.inputDelegate's native implementation of -[UITextInputDelegate selectionDidChange:].

// MyTextField.h

#import <UIKit/UIKit.h>

@interface MyTextField : UITextField

@end


// MyTextField.m

#import <objc/runtime.h>
#import "MyTextField.h"

UIKIT_STATIC_INLINE void mySelectionDidChange(id self, SEL _cmd, id<UITextInput> textInput);

@implementation MyTextField {
    BOOL swizzled;
}

#pragma mark - UIResponder

// Swizzle here because self.inputDelegate is set after becomeFirstResponder gets called.
- (BOOL)becomeFirstResponder {
    if ([super becomeFirstResponder]) {
        [self swizzleSelectionDidChange:YES];
        return YES;
    } else {
        return NO;
    }
}

// Unswizzle here because self.inputDelegate may become the inputDelegate for another UITextField.
- (BOOL)resignFirstResponder {
    if ([super resignFirstResponder]) {
        [self swizzleSelectionDidChange:NO];
        return YES;
    } else {
        return NO;
    }
}

#pragma mark - Swizzle -[UITextInput selectionDidChange:]

// Swizzle selectionDidChange: to "do whatever you want" when the text field's selection has changed.
// Only call this method on the main (UI) thread because it may not be thread safe.
- (void)swizzleSelectionDidChange:(BOOL)swizzle {
    if (swizzle == swizzled || ![self respondsToSelector:@selector(inputDelegate)]) return; // 4.3

    Class inputDelegateClass = object_getClass(self.inputDelegate);
    SEL mySelector = @selector(mySelectionDidChange:);
    class_addMethod(inputDelegateClass, mySelector, (IMP)mySelectionDidChange, "v@:@");
    Method myMethod    = class_getInstanceMethod(inputDelegateClass, mySelector);
    Method uiKitMethod = class_getInstanceMethod(inputDelegateClass, @selector(selectionDidChange:));
    method_exchangeImplementations(uiKitMethod, myMethod);
    swizzled = swizzle;
    // NSLog(@"swizzled? %i", method_getImplementation(uiKitMethod) == (IMP)venmo_selectionDidChange);
}

@end

UIKIT_STATIC_INLINE void mySelectionDidChange(id self, SEL _cmd, id<UITextInput> textInput) {
    // Call the native implementation of selectionDidChange:.
    [self performSelector:@selector(mySelectionDidChange:) withObject:textInput];

    // "Do whatever you want" with the selectedText below.
    NSString *selectedText = [textInput textInRange:textInput.selectedTextRange];
    NSLog(@"selectedText: %@", selectedText);        
}

这篇关于如何从iphone中的uitextfield中选择文本？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！