pist 最为持久化保存的一种方式！本身plist文件是xml ，对于小数量数据可以采用plis 的方法！这样更高效！废话不多说了！进入正题吧！如果是一个新手用plist的话一定会遇到各种问题！我当时就是这样走过来的！也是做个总结吧!
功能介绍：保存学生的基本信息：
一.
在故事板上拖拽几个控件吧如下图用来输入学生的信息
并在ViewController.h 里关联相应的控件！
@interface ViewController : UIViewController
@property (weak, nonatomic) IBOutlet UITextField *studentNumberTextField;
@property (weak, nonatomic) IBOutlet UITextField *studentNameTextField;
@property (weak, nonatomic) IBOutlet UITextField *studentnationTextField;
@property (weak, nonatomic)IBOutletUITextField *studentAgeTextFIeld;
二.创建一个保存学生信息的类 SaveStudentMessagePlist 并继承 NSObject
SaveStudentMessagePlist.h 文件里创建一个初始化的函数
#import <Foundation/Foundation.h>
@interface SaveStudentMessagePlist : NSObject
-(id)initWithStudentName:(NSString *)name Studentage:(NSString *)age StudentNumber:(NSString * )numerb StudentNation:(NSString *)nation;
@end
//在.m文件里实现方法///
-(id)initWithStudentName:(NSString *)name Studentage:(NSString *)age StudentNumber:(NSString * )numerb StudentNation:(NSString *)nation
{
//我们把学生的信息保存在可变数组里
NSMutableArray *studentMessageArray = [[NSMutableArray alloc]initWithObjects:name,age,numerb,nation,nil];
if (self = [superinit])
{
[self createStudentMessagePlist:studentMessageArraykey:numerb]; // 因为学生的学号是唯一的作为词典的key值
}
return self;
}
// 创建plist 写入操作
-(void)createStudentMessagePlist:(NSMutableArray *)studentMessageArray key:(NSString *)studentNumebr
{
//沙盒路径
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
// plist 路径
NSString *plistPath = [documentsDirectorystringByAppendingPathComponent:@"student.plist"];
NSFileManager *fileManager = [[NSFileManager alloc]init];
// 下面这几步很重要 通过文件管理器 来判读plist 文件是否存在！ 如果不存在 我们就通过 [fileManager createFileAtPath:plistPath contents:nil attributes:nil创建一个plist 并检测是否成功失败！存在后写入词典
如何存在plist 我们就 在 studentMessageDic 可变词典里保存在来色数据这样可以避免数据被覆盖问题
if(![fileManager fileExistsAtPath:plistPath])
{
if(![fileManager createFileAtPath:plistPathcontents:nilattributes:nil])
{
NSLog(@"create file error");
}
else
{
NSDictionary* studentMessageDic = [NSDictionary dictionaryWithObjectsAndKeys:studentMessageArray,studentNumebr ,nil];
[studentMessageDic writeToFile:plistPathatomically:YES];
}
}
else
{
NSMutableDictionary *studentMessageDic = [[NSMutableDictionary alloc]initWithContentsOfFile: plistPath];
[studentMessageDic setObject: studentMessageArray forKey:studentNumebr ];
[studentMessageDic writeToFile:plistPathatomically:YES];
}
}
现在让我们调用方法吧！ 打印路径plistPath 我们在沙盒里就会找到你的文件了如下图
-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
if (![studentNumberTextField.tex tisEqualToString:@"" ])
{
SaveStudentMessagePlist *save = [[SaveStudentMessagePlist alloc]initWithStudentName:studentNameTextField.textStudentage:studentAgeTextFIeld.textStudentNumber:studentNumberTextField.textStudentNation:studentnationTextField.text];
}
}
三 对plist 经行读操作
我创建了一个只定义的tableview 来显示学生的信息
-(void)readStudentMessageFromPlist
{
//创建文件管理器
NSFileManager *fileManager = [NSFileManager defaultManager];
NSArray *path = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString *documentation = [path objectAtIndex:0];
//更改到待操作的目录下
[fileManager changeCurrentDirectoryPath:[documentationstringByExpandingTildeInPath]];
NSString *studentPlistPath = [documentation stringByAppendingPathComponent:@"student.plist"];
_studentMessageDic = [[NSMutableDictionary alloc]initWithContentsOfFile:studentPlistPath];
NSLog(@"%d", [_studentMessageDicallKeys].count);
}
然后在tableview上显示
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
return [[_studentMessageDicallKeys]count];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *keyValue = [[_studentMessageDic allKeys]objectAtIndex:indexPath.row];
NSArray *studenMessageArr = [_studentMessageDic objectForKey:keyValue];
static NSString *CellIdentifier =@"Cell";
StudentCell *cell = (StudentCell *)[tableView dequeueReusableCellWithIdentifier:@"StudentCell"];
if (cell == nil)
{
if (cell == nil)
{
cell = [[StudentCellalloc]initWithStyle: UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
}
cell.name.text = [studenMessageArrobjectAtIndex:0];
cell.age.text = [studenMessageArrobjectAtIndex:1];
cell.number.text = [studenMessageArrobjectAtIndex:2];
cell.national.text = [studenMessageArrobjectAtIndex:3];
return cell;
}
当我们输入多个学生信息的时候我们会发现！数据根本不是按顺序显示的！(⊙_⊙)？ 我们在plist表里明明看的是顺序写入的，但是显示的时候确是随机的！这时候应该想到的是排序！ 好吧我把key 经行排序！
其实我们把红色 key 的那段函数改成下面的就可以了
NSArray *keyArray = [[_studentMessageDic allKeys]sortedArrayUsingSelector:@selector(compare:)]; //经行排序
NSString *keyValue = [ keyArray objectAtIndex:indexPath.row];
眼见为实 如图
！
四 这时候如果一个学生转学了！我们就要删除他的信息
这时候我们需要把以前的代码小改变下
我们把排序放在读取plist函数（-(void)readStudentMessageFromPlist）里更好！并设置为全局变量
_keyArray = [[_studentMessageDic allKeys]sortedArrayUsingSelector:@selector(compare:)];
并把路径也改完全局的
在tableview的委托里进行删除
-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
[self.tableViewbeg inUpdates];
if (editingStyle ==UITableViewCellEditingStyleDelete)
{
[_studentMessageDic removeObjectForKey:[_keyArray objectAtIndex:indexPath.row]];
[_studentMessageDic writeToFile:_studentPlistPath atomically:YES];
[self.tableView deleteRowsAtIndexPaths:[NSMutableArray arrayWithObject: indexPath ]withRowAnimation:UITableViewRowAnimationAutomatic];
}
[self.tableView endUpdates];
}
现在就只有小花了
看下效果吧：
五 这时候一位老师输入一个新同学叫小米！但是不小心学号输入错了输入了小花的学号！发现小花的信息出被替换了！这时候程序员又要做个判读了！
我在存入前遍历了下plist 如果存在就不进行写入操作 ，这样可以避免保存相同的数据！
// 创建plist
-(void)createStudentMessagePlist:(NSMutableArray *)studentMessageArray key:(NSString *)studentNumebr
{
BOOL isOrSava = YES;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *plistPath = [documentsDirectory stringByAppendingPathComponent:@"student.plist"];
NSFileManager *fileManager = [[NSFileManageralloc]init];
NSMutableDictionary *studentMessageDic = [NSMutableDictionarydictionaryWithContentsOfFile:plistPath];
if ([studentMessageDic count] >= 1)
{
//遍历key
for (id objin [studentMessageDic allKeys])
{
NSString *objstring = obj;
if ([[studentMessageArray objectAtIndex:2] isEqualToString:objstring])
{
isOrSava = NO; // 如果存在设置为NO
NSLog(@"学号以存在");
break;
}
}
if (isOrSava == YES)
{
if(![fileManager fileExistsAtPath:plistPath])
{
if(![fileManager createFileAtPath:plistPath contents:nilattributes:nil])
{
NSLog(@"create file error");
}
else
{
NSDictionary* studentMessageDic = [NSDictionary dictionaryWithObjectsAndKeys:studentMessageArray,studentNumebr ,nil];
[studentMessageDic writeToFile:plistPathatomically:YES];
}
}
else
{
NSMutableDictionary *studentMessageDic= [[NSMutableDictionary alloc]initWithContentsOfFile:plistPath];
[studentMessageDic setObject:studentMessageArray forKey:studentNumebr ];
[studentMessageDic writeToFile:plistPath atomically:YES];
}
}
}else
{
if(![fileManager fileExistsAtPath:plistPath])
{
if(![fileManager createFileAtPath:plistPath contents:nilattributes:nil])
{
NSLog(@"create file error");
}
else
{
NSDictionary* studentMessageDic = [NSDictionarydictionaryWithObjectsAndKeys:studentMessageArray,studentNumebr ,nil];
[studentMessageDic writeToFile:plistPathatomically:YES];
}
}
else
{
NSMutableDictionary *studentMessageDic= [[NSMutableDictionaryalloc]initWithContentsOfFile:plistPath];
[studentMessageDic setObject: studentMessageArray forKey:studentNumebr ];
[studentMessageDic writeToFile:plistPathatomically:YES];
}
}
}
六 又过了几天 老师找到程序员说！我要可以修改学生的年龄！可是当时的需求没有要求呀！找知道可以修改不如用数据库 ，coredata ，可是这是一个很懒的程序员！我想直接对plist 经行修改吧！
点击cell 显示当前学生的年龄 改成你想改的年龄 然后返回首页 改成15 了 很懒的程序员只是加了几行代码
用到 atIndexedSubscript 插入函数 把这个学习的年龄修改后在重新写入了plist
- (IBAction)SaveMessage:(id)sender
{
[_insterstudenMessage setObject:_ageTextField.text atIndexedSubscript:1];
NSMutableDictionary *studenDic = [[NSMutableDictionary alloc]init];
[studenDic setValue:_insterstudenMessageforKey:[_insterstudenMessage objectAtIndex:2]];
[studenDic writeToFile :_path atomically:YES];
}
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