iOS懒加载

// ViewController.m

#import "ViewController.h"

@interface ViewController ()
@property (nonatomic, strong) NSArray *shops;
@end

@implementation ViewController

// 懒加载
// 1.第一次用到时再去加载
// 2.只会加载一次
- (NSArray *)shops
{
    if (_shops == nil) {
        // 获得plist文件的全路径
        NSString *file = [[NSBundle mainBundle] pathForResource:@"shops.plist" ofType:nil];

        // 从plist文件中加载一个数组对象
        _shops = [NSArray arrayWithContentsOfFile:file];
    }
    return _shops;
}

// shop.h

#import <Foundation/Foundation.h>

@interface Shop : NSObject
/** 名字 */
@property (nonatomic, strong) NSString *name;
/** 图标 */
@property (nonatomic, strong) NSString *icon;
@end

// ViewController.m

#import "ViewController.h"
#import "Shop.h"

@interface ViewController ()
@property (nonatomic, strong) NSMutableArray *shops;
@end

@implementation ViewController

// 懒加载
// 1.第一次用到时再去加载
// 2.只会加载一次
- (NSMutableArray *)shops
{
    if (_shops == nil) {
        // 创建"模型数组"
        _shops = [NSMutableArray array];

        // 获得plist文件的全路径
        NSString *file = [[NSBundle mainBundle] pathForResource:@"shops.plist" ofType:nil];

        // 从plist文件中加载一个数组对象(这个数组中存放的都是NSDictionary对象)
        NSArray *dictArray = [NSArray arrayWithContentsOfFile:file];

        // 将 “字典数组” 转换为 “模型数据”
        for (NSDictionary *dict in dictArray) { // 遍历每一个字典
            // 将 “字典” 转换为 “模型”
            Shop *shop = [[Shop alloc] init];
            shop.name = dict[@"name"];
            shop.icon = dict[@"icon"];

            // 将 “模型” 添加到 “模型数组中”
            [_shops addObject:shop];
        }
    }
    return _shops;
}

#import <Foundation/Foundation.h>

@interface ZXShop : NSObject
/** 名字 */
@property (nonatomic, copy) NSString *name;
/** 图标 */
@property (nonatomic, copy) NSString *icon;

/** 通过一个字典来初始化模型对象 */
- (instancetype)initWithDict:(NSDictionary *)dict;

/** 通过一个字典来创建模型对象 */
+ (instancetype)shopWithDict:(NSDictionary *)dict;
@end

#import "ZXShop.h"

@implementation ZXShop

- (instancetype)initWithDict:(NSDictionary *)dict
{
    if (self = [super init]) {
        self.name = dict[@"name"];
        self.icon = dict[@"icon"];
    }
    return self;
}

+ (instancetype)shopWithDict:(NSDictionary *)dict
{
    // 这里要用self
    return [[self alloc] initWithDict:dict];
}

@end

#import "ViewController.h"
#import "ZXShop.h"

@interface ViewController ()
@property (nonatomic, strong) NSMutableArray *shops;
@end

@implementation ViewController

// 懒加载
// 1.第一次用到时再去加载
// 2.只会加载一次
- (NSMutableArray *)shops
{
    if (_shops == nil) {
        // 创建"模型数组"
        _shops = [NSMutableArray array];

        // 获得plist文件的全路径
        NSString *file = [[NSBundle mainBundle] pathForResource:@"shops.plist" ofType:nil];

        // 从plist文件中加载一个数组对象(这个数组中存放的都是NSDictionary对象)
        NSArray *dictArray = [NSArray arrayWithContentsOfFile:file];

        // 将 “字典数组” 转换为 “模型数据”
        for (NSDictionary *dict in dictArray) { // 遍历每一个字典
            // 将 “字典” 转换为 “模型”
            ZXShop *shop = [ZXShop shopWithDict:dict];

            // 将 “模型” 添加到 “模型数组中”
            [_shops addObject:shop];
        }
    }
    return _shops;
}