第十四篇、常用的分类文件

#import <Foundation/Foundation.h>

@interface NSArray (Category)
//以下写法均防止闪退
+ (instancetype)safeArrayWithObject:(id)object;

- (id)safeObjectAtIndex:(NSUInteger)index;

- (NSArray *)safeSubarrayWithRange:(NSRange)range;

- (NSUInteger)safeIndexOfObject:(id)anObject;

//通过Plist名取到Plist文件中的数组
+ (NSArray *)arrayNamed:(NSString *)name;

// 数组转成json 字符串
- (NSString *)toJSONStringForArray;
@end

#import "NSArray+Category.h"

@implementation NSArray (Category)
- (id)safeObjectAtIndexedSubscript:(NSUInteger)index
{
    if (index >= self.count) {
        return nil;
    } else {
        return [self objectAtIndex:index];
    }
}

- (id)safeObjectAtIndex:(NSUInteger)index
{
    if (index >= self.count) {
        return nil;
    } else {
        return [self objectAtIndex:index];
    }
}

+ (instancetype)safeArrayWithObject:(id)object
{
    if (object == nil) {
        return [self array];
    } else {
        return [self arrayWithObject:object];
    }
}

- (NSArray *)safeSubarrayWithRange:(NSRange)range
{
    NSUInteger location = range.location;
    NSUInteger length = range.length;
    if (location + length > self.count) {
        //超过了边界,就获取从loction开始所有的item
        if ((location + length) > self.count) {
            length = (self.count - location);
            return [self safeSubarrayWithRange:NSMakeRange(location, length)];
        }
        
        return nil;
    }
    else {
        return [self subarrayWithRange:range];
    }
}

- (NSUInteger)safeIndexOfObject:(id)anObject
{
    if (anObject == nil) {
        return NSNotFound;
    } else {
        return [self indexOfObject:anObject];
    }
}

+ (NSArray *)arrayNamed:(NSString *)name
{
    NSString *path = [[NSBundle mainBundle] pathForResource:name ofType:@"plist"];
    return [NSArray arrayWithContentsOfFile:path];
}


- (NSString *)toJSONStringForArray
{
    NSData *paramsJSONData = [NSJSONSerialization dataWithJSONObject:self options:0 error:nil];
    return [[NSString alloc] initWithData:paramsJSONData encoding:NSUTF8StringEncoding];
}
@end

#import <Foundation/Foundation.h>

@interface NSDictionary (Category)

//用于数据解析，返回对象为字符串或值类型，数组和字典不要用此方法
- (id)safeObjectForKey:(NSString *)key;

//设置键值对 针对对象为空处理
- (void)safeSetObject:(id)object forKey:(id)key;
- (id)objectForKeyCustom:(id)aKey;

- (id)safeKeyForValue:(id)value;

/**
 *  字段转成json的字符串
 *
 *  @return json 字符串
 */
- (NSString *)toJSONStringForDictionary;
@end

#import "NSDictionary+Category.h"


@implementation NSDictionary (Category)

- (id)safeObjectForKey:(NSString *)key {
    if (key == nil || [self isKindOfClass:[NSNull class]]) {
        return nil;
    }
    id object = [self objectForKey:key];
    if (object==nil || object == [NSNull null]) {
        return @"";
    }
    return object;
}


- (void)safeSetObject:(id)object forKey:(id)key {
    if ([key isKindOfClass:[NSNull class]]) {
        return;
    }
    if ([object isKindOfClass:[NSNull class]]) {
        [self setValue:@"" forKey:key];
    }else{
        [self setValue:object forKey:key];
    }
}

- (id)objectForKeyCustom:(id)aKey {
    id object   = nil;
    
    // 检查是否字典对象
    if (![self isKindOfClass:[NSDictionary class]]) {
        return object;
    }
    
    // 保证key必须为字符串
    if (aKey && [aKey isKindOfClass:[NSString class]]) {
        object  = [self objectForKeyCustom:aKey];
    }
    
    return object;
}

- (id)safeKeyForValue:(id)value {
    for (id key in self.allKeys) {
        if ([value isEqual:[self objectForKey:key]]) {
            return key;
        }
    }
    return nil;
}

- (NSString *)toJSONStringForDictionary
{
    NSData *paramsJSONData = [NSJSONSerialization dataWithJSONObject:self options:0 error:nil];
    return [[NSString alloc] initWithData:paramsJSONData encoding:NSUTF8StringEncoding];
}

@end