"IOS" Desctiption and Debugdescription

First, Introduction

Like. NET, the object object on the. NET has a ToString () method that can be used to output the object's information, and NSObject on iOS also has a method for description, which returns a description of the OBJC object, This method is called when we call NSLog to print an object or nsstring format the output of an object, and NSObject has another method debugdescription, which is used to output information in the debug console (in the console output object information such as: PO person), Debugdescription called by default when the description method

Second, the demonstration

@interface*float  weight; @end @implementation  Person @end

Person

Person *person =[[Person alloc] init];p erson.name=@"Bomo";p erson.age= -;p erson.weight=134; NSString*logmessage = [NSString stringWithFormat:@"%@", person]; NSLog (@"stringWithFormat:%@", LogMessage); NSLog (@"NSLog:%@", person);

By default, the Object-c object only outputs the address of the object name and object

The default implementation should look like this

-(NSString *) description{    return [nsstring stringWithFormat:@ "<%@:%p>  "class"), self];}

Usually we want to see more properties of the class information, we can override the description method

@interfacePerson:nsobject@property (nonatomic, assign) Nsuinteger age; @property (nonatomic, copy) NSString*Name: @property (nonatomic, assign) Nsuinteger gender; @property (nonatomic, assign)floatweight;@end@implementation Person-(NSString *) description{return[NSString stringWithFormat:@"<person:%p> {\n\tname=%@,\n\tage=%ld,\n\tweight=%f,\n\tgender=%lu\n}", Self, self.name, self.age, Self.weight, Self.gender];}@end

Output the following information

Three, Package

In fact, we can encapsulate a common method, through the runtime API dynamically get to the object type, and output, here to create a base class Basemodel, we implement a common description method in the base class

@interfaceBasemodel:nsobject@end@implementationBasemodel-(NSString *) description1{IDModelclass = [Selfclass]; unsignedintOutcount, I; objc_property_t*properties = Class_copypropertylist (Modelclass, &outcount); Nsmutabledictionary*dict =[Nsmutabledictionary Dictionarywithcapacity:outcount]; //iterate through all the attributes Key/value     for(i =0; i < Outcount; i++) {objc_property_t property=Properties[i]; NSString*propname =[NSString Stringwithutf8string:property_getname (property)]; IDValue =[[Self valueforkey:propname] description];    [Dict Setobject:value Forkey:propname]; }    return[NSString stringWithFormat:@"<%@:%p>%@", Nsstringfromclass ([selfclass]), self, Dict];}-(NSString *) debugdescription{return[self description];}@end

This is our person class only need to inherit from Basemodel can implement such as nsdictionary output, here is the use of the output of the dictionary, you do not have to spell the string

There is another way to achieve this custom output through the base class method, and the method swizzling can be used to replace NSObject's original description methods.

See also: http://www.cnblogs.com/bomo/p/4693363.html

"IOS" Desctiption and Debugdescription