Question

如何修改plist文件

Answer 1

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;
}