ios学习笔记（二）－－－－－ios中对文件的操作

效果如下图：

主要是实现功能，界面随便弄的。

代码如下：

ViewController。h

#import <UIKit/UIKit.h>

@interface ViewController : UIViewController<UITextFieldDelegate>

@property (retain, nonatomic) IBOutlet UILabel *mylabel;

@property (retain, nonatomic) IBOutlet UITextField *mytextfield;

@property (retain, nonatomic) IBOutlet UIButton *writeFileBtn;

@property (retain, nonatomic) IBOutlet UIButton *readFileBtn;

- (IBAction)writeBtnClick:(id)sender;
- (IBAction)readBtnClick:(id)sender;

@end

ViewController。m

#import "ViewController.h"

@interface ViewController ()
@end
@implementation ViewController

@synthesize mylabel;
@synthesize mytextfield;
@synthesize writeFileBtn;
@synthesize readFileBtn;

- (void)viewDidLoad
{
    [super viewDidLoad];
//    主要实现在文本框中输入文字时，防止文本框被弹出的键盘挡住。实现UITextFieldDelegate委托中的3个方法即可解决。
    mytextfield.delegate=self;
    
//    ios6.0中UITextAlignmentCenter 已经是反对状态了，要用下面的NSTextAlignmentCenter替换
    mylabel.textAlignment=NSTextAlignmentCenter;
//    这3行用来实现，label宽度的自适应， 效果相当于android布局中wrap_content
    [mylabel setNumberOfLines:0];
    mylabel.text=@"我是label，我用来显示文件中的内容";
    [mylabel sizeToFit];
    
    
    NSString *str1=@"将文本框的内容写入文件";
    NSString *str2=@"文件中的内容读取label上";
    
    [writeFileBtn setTitle:str1 forState:UIControlStateNormal];
    [readFileBtn  setTitle:str2 forState:UIControlStateNormal];
    
  
    
}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

- (void)dealloc {
    [mylabel release];
    [mytextfield release];
    [writeFileBtn release];
    [readFileBtn release];
    [super dealloc];
}




- (void)keyboardWillShow:(NSNotification *)noti
{
    //键盘输入的界面调整
    //键盘的高度
    float height = 216.0;
    CGRect frame = self.view.frame;
    frame.size = CGSizeMake(frame.size.width, frame.size.height - height);
    [UIView beginAnimations:@"Curl"context:nil];//动画开始
    [UIView setAnimationDuration:0.30];
    [UIView setAnimationDelegate:self];
    [self.view setFrame:frame];
    [UIView commitAnimations];
}


- (BOOL)textFieldShouldReturn:(UITextField *)textField
{
    // When the user presses return, take focus away from the text field so that the keyboard is dismissed.
    NSTimeInterval animationDuration = 0.30f;
    [UIView beginAnimations:@"ResizeForKeyboard" context:nil];
    [UIView setAnimationDuration:animationDuration];
    CGRect rect = CGRectMake(0.0f, 0.0f, self.view.frame.size.width, self.view.frame.size.height);
    self.view.frame = rect;
    [UIView commitAnimations];
    [textField resignFirstResponder];
    return YES;
}


- (void)textFieldDidBeginEditing:(UITextField *)textField
{
    CGRect frame = textField.frame;
    int offset = frame.origin.y + 32 - (self.view.frame.size.height - 216.0);//键盘高度216
    NSTimeInterval animationDuration = 0.30f;
    [UIView beginAnimations:@"ResizeForKeyBoard" context:nil];
    [UIView setAnimationDuration:animationDuration];
    float width = self.view.frame.size.width;
    float height = self.view.frame.size.height;
    if(offset > 0)
    {
        CGRect rect = CGRectMake(0.0f, -offset,width,height);
        self.view.frame = rect;
    }
    [UIView commitAnimations];
}

//写文件的操作
-(void)writeFile:(NSString *)string
{
    //创建文件管理器
    NSFileManager *fileManager = [NSFileManager defaultManager];
    
    //获取路径
    //1、参数NSDocumentDirectory要获取的那种路径
    NSArray*  paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    //2、得到相应的Documents的路径
    NSString  *str = [paths objectAtIndex:0];
    //3、更改到待操作的目录下
    [fileManager changeCurrentDirectoryPath:[str stringByExpandingTildeInPath]];
    //4、创建文件fileName文件名称，contents文件的内容，如果开始没有内容可以设置为nil，attributes文件的属性，初始为nil
    [fileManager removeItemAtPath:@"mytest" error:nil];
    NSString *path = [str stringByAppendingPathComponent:@"mytest"];
    //5、创建数据缓冲区
    NSMutableData  *writer = [[NSMutableData alloc] init];
    //6、将字符串添加到缓冲中
    [writer appendData:[string dataUsingEncoding:NSUTF8StringEncoding]];
    //7、将其他数据添加到缓冲中
    //将缓冲的数据写入到文件中
    [writer writeToFile:path atomically:YES];
    [writer release];
    
}
//读文件
- (NSString *)readFile
{
    //创建文件管理器
    NSFileManager *fileManager = [NSFileManager defaultManager];
    //获取路径
    NSArray  *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    
    [fileManager changeCurrentDirectoryPath:[documentsDirectory stringByExpandingTildeInPath]];
    
    //获取文件路径
    NSString* path = [documentsDirectory stringByAppendingPathComponent:@"mytest"];
    NSData* reader = [NSData dataWithContentsOfFile:path];
    return [[NSString alloc] initWithData:reader encoding:NSUTF8StringEncoding];
}


//写文件的按钮的监听
- (IBAction)writeBtnClick:(id)sender {
   
    [self writeFile:mytextfield.text];
}
//读文件的按钮的监听
- (IBAction)readBtnClick:(id)sender {
   
    mylabel.text=[self readFile];
}
@end