List of---Properties for iOS data persistence

Attribute list (plist)

iOS provides a plist format file (a list of attributes) for storing lightweight data, and only Nsdictionary, Nsarray, NSString, NSNumber, Boolean, NSData, and nsdate types of data can be saved. Save these types of data in a plist format file that can be read directly using Nsdictionary and Nsarray

(i), the use of nsuserdefault to achieve persistence

The following is a list of nsuserdefault locally saved locations, which are mentioned in the Data Persistence sandbox directory. Library/preferences the plist file in this directory is its saved directory.
The use of Nsuserdefault is mainly to save and read

Initialize a Nsuserdefault

 　 　+ (NSUserDefaults *)standardUserDefaults;

Ways to set up your data

- (void) SetObject: (NullableID) value Forkey: (NSString *) DefaultName; - (void) Setinteger: (nsinteger) value Forkey: (nsstring *) DefaultName; -(void) SetFloat: (float) value Forkey: (　 　nsstring *) DefaultName; -(void) setdouble: (double) value Forkey: (nsstring *) DefaultName; -(void) Setbool: (bool) value Forkey: (　　 nsstring *) DefaultName; -(void) SetUrl: (Nullable nsurl *) URL Forkey: (nsstring *) defaultname ns_available (10_6, Span class= "Hljs-number" >4_0)              

How to read data:

- (NullableIdObjectforkey:(NSString *) DefaultName;- (NullableNSString *)Stringforkey:(NSString *) DefaultName;- (NullableNsarray *)Arrayforkey:(NSString *) DefaultName;- (Nullablensdictionary<NSString *,Id> *)Dictionaryforkey:(NSString *) DefaultName;- (NullableNSData *)Dataforkey:(NSString *) DefaultName;- (Nullablensarray<NSString *> *)Stringarrayforkey:(NSString *) DefaultName;- (Nsinteger)Integerforkey:(NSString *) DefaultName;-(float) 　 　Floatforkey:-(double) 　 　Doubleforkey:-(bool) 　 　Boolforkey:-(nullable nsurl *)  urlforkey: (NSString *) defaultname ns_available (10_6, 4_0);    

Ways to delete data:

　  　- (void)removeObjectForKey:(NSString *)defaultName;

Save data:

  　　 // 如果不手动调用，系统会自动保存，但时间不定

　 　- (BOOL)synchronize;
　

　　　// 存储id类型数据

+ (void) SetValue: (ID) value Andkey: (NSString *) key

{

Nsuserdefaults *userdefaults = [Nsuserdefaults standarduserdefaults];

[Userdefaults Setobject:value Forkey:key];

[Userdefaults Synchronize];

}

　　　　// 获取数据

+ (NSString *) Getvaluebykey: (NSString *) key

{

Nsuserdefaults * settings = [Nsuserdefaults standarduserdefaults];

NSString *value = [Settings Objectforkey:key];

return value;

}

(ii), manually add the plist file

　　New File-->resource-->property List

　　　　The root type of the plist file can only be Nsarray or nsdictionary

　　　　

read the data in the plist file into the corresponding root type

　　　　1. Get the path where the file is located, Resource: file name, Type: file format

　　　　NSString *filepath = [[nsbundle Mainbundle] Pathforresource:@ "Userinfos" OfType:@ "plist"];

　　　　2. Get the data in the corresponding format from the path

　　　　If Root is Nsarray, the array is used to save

　　　　Nsarray *infos = [nsarray arraywithcontentsoffile:filepath];

　　　　NSLog (@ "%@", infos);

< Span class= "hljs-string" > //if Root is nsdictionary, use dictionary to save

< Span class= "hljs-string" > nsdictionary *infodic = [ Nsdictionary Dictionarywithcontentsoffile:filepath];

　　　　NSLog (@ "%@", infodic);

(iii), direct data written to the plist file

Because Nsuserdefault is essentially the persistence of attributes through the plist file. Therefore, we can create a plist file by ourselves to achieve the persistence of the property.

 　　       Nsarray *path =Nssearchpathfordirectoriesindomains (NSDocumentDirectory,Nsuserdomainmask,YES); nsstring *docpath = [path Objectatindex:0]; nsstring *myfile = [DocPath stringbyappendingpathcomponent:@ "Test.plist"]; nsmutabledictionary *contentdic; //Determine if there is a local plist fileif ([[Nsfilemanager Defaultmanager] fileexistsatpath:myfile] = =NO) {nsfilemanager* fm = [nsfilemanager Defaultmanager];  //create a file [FM createfileatpath:myfile contents:
                      nil attributes:  　　 nil "; 　　 Contentdic = [[ nsmutabledictionary alloc] init]; } else {contentdic = [[nsmutabledictionary Alloc] InitWithCon 　　 Tentsoffile:myfile]; } //data read and write operations [Contentdic setobject:@ "1234" Forkey:@ "PassWord"]; //save modified data to plist file [contentdic writetofile:myfile Atomically:yes";             

(iv), summary
　　　　The plist file reads and writes more efficiently, because his read and write needs to take all the data out and then save it all, so it is only suitable for small data.

List of---Properties for iOS data persistence