您应该尝试以编程方式绘制线条,而不是使用图像。以下是一些示例代码,说明如何实现这一目标。你可以子类化UITextView
并覆盖它drawRect:
method.
NoteView.h
#import <UIKit/UIKit.h>
@interface NoteView : UITextView <UITextViewDelegate> {
}
@end
NoteView.m
#import "NoteView.h"
@implementation NoteView
- (id)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.backgroundColor = [UIColor colorWithRed:1.0f green:1.0f blue:0.6f alpha:1.0f];
self.font = [UIFont fontWithName:@"MarkerFelt-Thin" size:19];
}
return self;
}
- (void)drawRect:(CGRect)rect {
//Get the current drawing context
CGContextRef context = UIGraphicsGetCurrentContext();
//Set the line color and width
CGContextSetStrokeColorWithColor(context, [UIColor colorWithRed:0.0f green:0.0f blue:0.0f alpha:0.2f].CGColor);
CGContextSetLineWidth(context, 1.0f);
//Start a new Path
CGContextBeginPath(context);
//Find the number of lines in our textView + add a bit more height to draw lines in the empty part of the view
NSUInteger numberOfLines = (self.contentSize.height + self.bounds.size.height) / self.font.leading;
//Set the line offset from the baseline. (I'm sure there's a concrete way to calculate this.)
CGFloat baselineOffset = 6.0f;
//iterate over numberOfLines and draw each line
for (int x = 0; x < numberOfLines; x++) {
//0.5f offset lines up line with pixel boundary
CGContextMoveToPoint(context, self.bounds.origin.x, self.font.leading*x + 0.5f + baselineOffset);
CGContextAddLineToPoint(context, self.bounds.size.width, self.font.leading*x + 0.5f + baselineOffset);
}
//Close our Path and Stroke (draw) it
CGContextClosePath(context);
CGContextStrokePath(context);
}
@end
MyViewController.h
#import <UIKit/UIKit.h>
#import "NoteView.h"
@interface MyViewController : UIViewController <UITextViewDelegate> {
NoteView *note;
}
@property (nonatomic, retain) NoteView *note;
@end
MyViewController.m
#import "MyViewController.h"
#import "NoteView.h"
#define KEYBOARD_HEIGHT 216
@implementation MyViewController
@synthesize note;
- (void)loadView {
[super loadView];
self.note = [[[NoteView alloc] initWithFrame:self.view.bounds] autorelease];
[self.view addSubview:note];
note.delegate = self;
note.text = @"This is the first line.\nThis is the second line.\nThis is the ... line.\nThis is the ... line.\nThis is the ... line.\nThis is the ... line.\nThis is the ... line.\n";
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
[note setNeedsDisplay];
}
- (void)textViewDidBeginEditing:(UITextView *)textView {
CGRect frame = self.view.bounds;
frame.size.height -= KEYBOARD_HEIGHT;
note.frame = frame;
}
- (void)textViewDidEndEditing:(UITextView *)textView {
note.frame = self.view.bounds;
}
- (void)dealloc {
[note release];
[super dealloc];
}
看看苹果的文档管理键盘 http://developer.apple.com/library/ios/#documentation/StringsTextFonts/Conceptual/TextAndWebiPhoneOS/KeyboardManagement/KeyboardManagement.html,特别是“移动位于键盘下的内容”。它解释了如何监听 NSNotifcations 并正确调整您的视图。