Question

如何对.plist文件添加，删除数据

Answer 1

主要操作：
1.//获得plist路径 -(NSString*)getPlistPath；
2.//判断沙盒中名为plistname的文件是否存在 -(BOOL) isPlistFileExists；
3.//读取沙盒中Document文件夹下的BookList.plist文件
[NSMutableDictionarydictionaryWithContentsOfFile:plistPath];
4.//写入文件 if ([plistDictionary writeToFile:plistPath atomically:YES])

WBBooksManager.m文件：
#import "WBBooksManager.h"

@implementation WBBooksManager

static WBBooksManager *g_instance = nil;

+ (WBBooksManager *)sharedInstance
{
@synchronized(self) {
if ( g_instance == nil ) {
g_instance = [[self alloc] init];
}
}
return g_instance;
}

//获得plist路径
-(NSString*)getPlistPath{
//沙盒中的文件路径
NSArray *storeFilePath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *doucumentsDirectiory = [storeFilePath objectAtIndex:0];
NSString *plistPath =[doucumentsDirectiory stringByAppendingPathComponent:@"WBBooks.plist"]; //根据需要更改文件名
return plistPath;
}

//判断沙盒中名为plistname的文件是否存在
-(BOOL) isPlistFileExists{

NSString *plistPath =[[WBBooksManager sharedInstance]getPlistPath];
NSFileManager *fileManager = [NSFileManager defaultManager];
if( [fileManager fileExistsAtPath:plistPath]== NO ) {
NSLog(@"not exists");
return NO;
}else{
return YES;
}

}

-(void)initPlist{
NSString *plistPath = [[WBBooksManager sharedInstance] getPlistPath];

//如果plist文件不存在，将工程中已建起的plist文件写入沙盒中
if (! [[WBBooksManager sharedInstance] isPlistFileExists]) {

//从自己建立的plist文件 复制到沙盒中 ，方法一
NSError *error;
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *bundle = [[NSBundle mainBundle] pathForResource:@"WBBooks" ofType:@"plist"];
[fileManager copyItemAtPath:bundle toPath:plistPath error:&error];

//方法二
// NSString *path = [[NSBundle mainBundle] pathForResource:@"WBBooks"ofType:@"plist"];
// NSMutableDictionary *activityDics = [[NSMutableDictionary alloc] initWithContentsOfFile:path];
// [activityDics writeToFile:plistPath atomically:YES];
}
}

//判断key的书是否存在
-(BOOL)isBookExistsForKey:(NSString*)key{

NSString *plistPath = [[WBBooksManager sharedInstance] getPlistPath];
NSMutableDictionary *WBBooksDictionary = [[NSMutableDictionary alloc] initWithContentsOfFile:plistPath];

//根目录下存在名为bookname的字典
if ([WBBooksDictionary objectForKey:key]) {
return YES;
}else{
return NO;
}
}

//根据key值删除对应书籍
-(void)removeBookWithKey:(NSString *)key{

NSString *plistPath = [[WBBooksManager sharedInstance] getPlistPath];
NSMutableDictionary *WBBooksDictionary = [[NSMutableDictionary alloc] initWithContentsOfFile:plistPath];

[WBBooksDictionary removeObjectForKey:key];
[WBBooksDictionary writeToFile:plistPath atomically:YES]; //删除后重新写入

}

//删除plistPath路径对应的文件
-(void)deletePlist{

NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *plistPath = [[WBBooksManager sharedInstance] getPlistPath];
[fileManager removeItemAtPath:plistPath error:nil];

}

//将dictionary写入plist文件，前提：dictionary已经准备好
-(void)writePlist:(NSMutableDictionary*)dictionary forKey:(NSString *)key{

NSMutableDictionary *plistDictionary = [[NSMutableDictionary alloc]init];

//如果已存在则读取现有数据
if ([[WBBooksManager sharedInstance]isPlistFileExists]) {
plistDictionary = [[WBBooksManager sharedInstance]readPlist];
}

//增加一个数据
[plistDictionary setValue:dictionary forKey:key]; //在plistDictionary增加一个key为...的value

NSString *plistPath = [[WBBooksManager sharedInstance] getPlistPath];

if([plistDictionary writeToFile:plistPath atomically:YES]){
NSLog(@"write ok!");
}else{
NSLog(@"ddd");
}

}

//
-(NSMutableDictionary*)readPlist{

NSString *plistPath = [[WBBooksManager sharedInstance] getPlistPath];
NSMutableDictionary *resultDictionary = [[NSMutableDictionary alloc]initWithContentsOfFile:plistPath];
return resultDictionary;
}

//读取plist文件内容复制给dictionary 备用
-(void)readPlist:(NSMutableDictionary **)dictionary{
NSString *plistPath = [[WBBooksManager sharedInstance] getPlistPath];
*dictionary = [[NSMutableDictionary alloc] initWithContentsOfFile:plistPath];
}

//更改一条数据，就是把dictionary内key重写
-(void)replaceDictionary:(NSMutableDictionary *)newDictionary withDictionaryKey:(NSString *)key{

[[WBBooksManager sharedInstance]removeBookWithKey:key];
[[WBBooksManager sharedInstance]writePlist:newDictionary forKey:key];

}

-(NSInteger)getBooksCount{

NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
dictionary = [[WBBooksManager sharedInstance] readPlist];
return [dictionary count];

}