ios Singleton

UserInfoManagerCenter.h

#import <Foundation/Foundation.h>

@interface UserInfoManagerCenter : NSObject

@property (nonatomic,strong) NSString *name;
@property (nonatomic,strong) NSNumber *age;

+(instancetype)managerCenter;
@end

UserInfoManagerCenter.m

#import "UserInfoManagerCenter.h"
static UserInfoManagerCenter *center = nil;
@implementation UserInfoManagerCenter
+(instancetype)managerCenter{

    static dispatch_once_t predicate;
    // 避免產生競爭現像
    dispatch_once(&predicate, ^{
        center = (UserInfoManagerCenter *)@"UserInfoManagerCenter";
        center = [[UserInfoManagerCenter alloc] init];
    });
    
    // 防止子類別使用
    NSString *classString = NSStringFromClass([self class]);
    // 使用方法的class名字與UserInfoManagerCenter不同　就crash
    if( [classString isEqualToString:@"UserInfoManagerCenter"] == NO ){
        // crash
        NSParameterAssert(nil);
    }
    
    return center;
}

-(instancetype)init{
    NSString *string = (NSString*)center;
    if( [string isKindOfClass:[NSString class]] == YES && [string isEqualToString:@"UserInfoManagerCenter"]){
        self = [super init];
        if( self){
            // 防止子類別使用
            NSString *classString = NSStringFromClass([self class]);
            // 使用方法的class名字與UserInfoManagerCenter不同　就crash
            if( [classString isEqualToString:@"UserInfoManagerCenter"] == NO ){
                // crash
                NSParameterAssert(nil);
            }
            

        }
        return self;
    }else{
        return nil;
    }
    
    
}
@end

使用

UserInfoManagerCenter *center = [UserInfoManagerCenter managerCenter];

    NSLog(@"%@",center.name);