Accepting User Text Input with UITextField
textField在Interfa Builder中不能改变高度，但是在代码中可以，无论怎么改变其高度，行数始终是1
头文件
#import <UIKit/UIKit.h>
@interface ViewController : UIViewController<UITextFieldDelegate> //为了监听用户触发的事件，例如开始输入，完成输入等，text Field要有自己的代理，这个代理遵守协议
@property (nonatomic,strong) UITextField *textField;
@property (nonatomic,strong) UILabel *labelCounter;
@end
实现
#import "ViewController.h"
@interfaceViewController ()
@end
@implementation ViewController
- (void) calculateAndDisplayTextFieldLengthWithText: (NSString *) paramText {
NSString *characterOrCharacters = @"characters";
if (characterOrCharacters.length == 1) {
characterOrCharacters = @"charater";
}
self.labelCounter.text = [NSString stringWithFormat:@"%lu %@", (unsigned long)paramText.length, characterOrCharacters];
}
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
BOOL result = YES;
if ([textField isEqual:self.textField]){
NSString *wholeText =
[textField.textstringByReplacingCharactersInRange:range
withString:string];
[selfcalculateAndDisplayTextFieldLengthWithText:wholeText];
}
return result;
}
//Keyboard消失
- (BOOL)textFieldShouldReturn:(UITextField *)textField{ [textField resignFirstResponder];
returnYES;
}
- (void)viewDidLoad
{
[superviewDidLoad];
CGRect textFieldFrame = CGRectMake(38.0f, 30.0f, 250.f, 23.f);
self.textField = [[UITextField alloc] initWithFrame:textFieldFrame];
self.textField.delegate = self;
self.textField.borderStyle =UITextBorderStyleRoundedRect;
self.textField.contentVerticalAlignment = UIControlContentVerticalAlignmentCenter;//默认左上
self.textField.placeholder = @"Enter the text here…………";
//self.textField.center = self.view.center;
[self.view addSubview:self.textField];
CGRect labelCounterFrame = self.textField.frame;
labelCounterFrame.origin.y += textFieldFrame.size.height + 10;
self.labelCounter = [[UILabel alloc] initWithFrame:labelCounterFrame];
[self.viewaddSubview:self.labelCounter];
[selfcalculateAndDisplayTextFieldLengthWithText:self.textField.text];
UILabel *currencyLabel = [[UILabel alloc] initWithFrame:CGRectZero];
currencyLabel.text = [[[NSNumberFormatter alloc] init] currencySymbol];
currencyLabel.font = self.textField.font;
[currencyLabel sizeToFit];
self.textField.leftView = currencyLabel;
self.textField.leftViewMode = UITextFieldViewModeWhileEditing; //leftViewMode和rightViewMode两个property控制currencyLabel出现的形式，此时是用户输入text时出现
// typedef enum { UITextFieldViewModeNever,UITextFieldViewModeWhileEditing, UITextFieldViewModeUnlessEditing, UITextFieldViewModeAlways
// } UITextFieldViewMode;
}
- (void)didReceiveMemoryWarning
{
[superdidReceiveMemoryWarning];
}
@end
Displaying Long Lines of Text with UITextView ：keyboard不能将用户输入的text遮挡住
头文件
@interface ViewController : UIViewController
@property (nonatomic,strong) UITextView *myLongTextView;
@end
实现
#import "ViewController.h"
@interfaceViewController ()
@end
@implementation ViewController
- (void) handleKeyboardDidShow:(NSNotification *)paramNotification{
/* Get the frame of the keyboard */
NSValue *keyboardRectAsObject = [[paramNotification userInfo] //userInfo是NSDictionary类型的一个属性，其中一个key 是UIKeyboardFrameEndUserInfoKey，包括一个NSValue类型的keyboard的 boundaries，而这个boundaries放在一个CGRect中。
objectForKey:UIKeyboardFrameEndUserInfoKey];
/* Place it in a CGRect */
CGRect keyboardRect;
[keyboardRectAsObject getValue:&keyboardRect];
/* Give a bottom margin to our text view that makes it reach to the top of the keyboard */
self.myLongTextView.contentInset = UIEdgeInsetsMake(0.0f,
0.0f,
keyboardRect.
size.height,
0.0f);
}
- (void) handleKeyboardWillHide:(NSNotification *)paramNotification{
/* Make the text view as big as the whole view again */
self.myLongTextView.contentInset = UIEdgeInsetsZero;
}
/*在- (void) viewWillAppear:方法中开始looking for keyboard的notifications, 而在- (void) viewWillDisappear:方法中停止监听。让你的view controller停止监听是很重要的，因为当你的view controller不被display，那你不会希望接收其他的view controller引发的keyboard notifications. */
- (void) viewWillAppear:(BOOL)paramAnimated{
[super viewWillAppear:paramAnimated];
[[NSNotificationCenterdefaultCenter] addObserver:self
selector:@selector(handleKeyboardDidShow:)
name:UIKeyboardDidShowNotification
object:nil];
[[NSNotificationCenterdefaultCenter] addObserver:self
selector:@selector(handleKeyboardWillHide:)
name:UIKeyboardWillHideNotification
object:nil];
self.view.backgroundColor = [UIColorwhiteColor];
self.myLongTextView = [[UITextViewalloc] initWithFrame:self.view.bounds];
self.myLongTextView.text = @"Some text here...";
self.myLongTextView.font = [UIFontsystemFontOfSize:16.0f];
[self.viewaddSubview:self.myLongTextView];
}
- (void) viewWillDisappear:(BOOL)paramAnimated{
[super viewWillDisappear:paramAnimated];
[[NSNotificationCenterdefaultCenter] removeObserver:self];
}
@end
<UITextFieldDelegate> 中都是可选的方法：
- (BOOL)textFieldShouldBeginEditing:(UITextField *)textField; // return NO to disallow editing.
- (void)textFieldDidBeginEditing:(UITextField *)textField; // became first responder
- (BOOL)textFieldShouldEndEditing:(UITextField *)textField; // return YES to allow editing to stop and to resign first responder status. NO to disallow the editing session to end
- (void)textFieldDidEndEditing:(UITextField *)textField; // may be called if forced even if shouldEndEditing returns NO (e.g. view removed from window) or endEditing:YES called
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string; // return NO to not change text
- (BOOL)textFieldShouldClear:(UITextField *)textField; // called when clear button pressed. return NO to ignore (no notifications)
- (BOOL)textFieldShouldReturn:(UITextField *)textField; // called when 'return' key pressed. return NO to ignore.
