NSLog 解决中文乱码并显示成JSON格式

引言:

文章的初衷很简单，是为了能够正常显示打印出字典里面的中文。因为默认情况下，直接打印字典的话，在Xcode控制台上，中文会是乱码的，需要Unicode转码才能看到中文。

一. 正常打印

NSDictionary *dict = @{@"name":@"张三",
                       @"job":@"iOS开发工程是",
                       	@"author":@{@"nickName":@"谦言忘语",
                       		@"blog":@"https://www.jianshu.com/u/cc2cf725ac0c",
                       		@"work":@"iOS工程师"}
                       };
NSLog(@"打印出的字典：%@",dict);

打印结果：

二. 解决方案

利用runtime的方法交换 来实现：

/// DEBUG模式生效
#ifdef DEBUG

#import "SQPrintJsonLog.h"
#import <objc/runtime.h>

#pragma mark - 方法交换

static inline void sq_swizzleSelector(Class class, SEL originalSelector, SEL swizzledSelector) {
    
    Method originalMethod = class_getInstanceMethod(class, originalSelector);
    Method swizzledMethod = class_getInstanceMethod(class, swizzledSelector);
    
    BOOL didAddMethod = class_addMethod(class,
                                        originalSelector,
                                        method_getImplementation(swizzledMethod),
                                        method_getTypeEncoding(swizzledMethod));
    if (didAddMethod) {
        class_replaceMethod(class,
                            swizzledSelector,
                            method_getImplementation(originalMethod),
                            method_getTypeEncoding(originalMethod));
    } else {
        method_exchangeImplementations(originalMethod, swizzledMethod);
    }
}


#pragma mark - --- NSObject 分类 ---

@implementation NSObject (SQJSON)

/// 将obj转换成json字符串。如果失败则返回nil.
- (NSString *)convertToJsonString {
    
    //先判断是否能转化为JSON格式
    if (![NSJSONSerialization isValidJSONObject:self])  return nil;
    NSError *error = nil;
    NSData *jsonData = [NSJSONSerialization dataWithJSONObject:self options:NSJSONWritingPrettyPrinted  error:&error];
    if (error || !jsonData) return nil;
    NSString *jsonString = [[NSString alloc] initWithData:jsonData encoding:NSUTF8StringEncoding];
    return jsonString;
}

@end


#pragma mark - ---NSDictionary 分类 ---

@implementation NSDictionary (SQJsonLog)

/// 用此方法交换系统的 descriptionWithLocale: 方法。该方法在代码打印的时候调用。
- (NSString *)sqjsonlog_descriptionWithLocale:(id)locale{

    NSString *result = [self convertToJsonString];//转换成JSON格式字符串
    if (!result) return [self sqjsonlog_descriptionWithLocale:locale];//如果无法转换，就使用原先的格式
    return result;
}

/// 用此方法交换系统的 descriptionWithLocale:indent:方法。功能同上。
- (NSString *)sqjsonlog_descriptionWithLocale:(id)locale indent:(NSUInteger)level {
    
    NSString *result = [self convertToJsonString];
    if (!result) return [self sqjsonlog_descriptionWithLocale:locale indent:level];
    return result;
}
/// 用此方法交换系统的 debugDescription 方法。该方法在控制台使用po打印的时候调用。
- (NSString *)sqjsonlog_debugDescription{
    
    NSString *result = [self convertToJsonString];
    if (!result) return [self sqjsonlog_debugDescription];
    return result;
}

/// 在load方法中完成方法交换
+ (void)load {
    
    //方法交换
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        
        Class class = [self class];
        sq_swizzleSelector(class, @selector(descriptionWithLocale:), @selector(sqjsonlog_descriptionWithLocale:));
        sq_swizzleSelector(class, @selector(descriptionWithLocale:indent:), @selector(sqjsonlog_descriptionWithLocale:indent:));
        sq_swizzleSelector(class, @selector(debugDescription), @selector(sqjsonlog_debugDescription));
    });
}

@end


#pragma mark - --- NSArray 分类 ---

@implementation NSArray (SQJsonLog)

/// 用此方法交换系统的 descriptionWithLocale: 方法。该方法在代码打印的时候调用。
- (NSString *)sqjsonlog_descriptionWithLocale:(id)locale{
    
    NSString *result = [self convertToJsonString];
    if (!result) return [self sqjsonlog_descriptionWithLocale:locale];
    return result;
}

/// 用此方法交换系统的 descriptionWithLocale:indent:方法。功能同上。
- (NSString *)sqjsonlog_descriptionWithLocale:(id)locale indent:(NSUInteger)level {
    
    NSString *result = [self convertToJsonString];
    if (!result) return [self sqjsonlog_descriptionWithLocale:locale indent:level];
    return result;
}


/// 用此方法交换系统的 debugDescription 方法。该方法在控制台使用po打印的时候调用。
- (NSString *)sqjsonlog_debugDescription{
    
    NSString *result = [self convertToJsonString];
    if (!result) return [self sqjsonlog_debugDescription];
    return result;
}

+ (void)load {
    
    //方法交换
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        
        Class class = [self class];
        sq_swizzleSelector(class, @selector(descriptionWithLocale:), @selector(sqjsonlog_descriptionWithLocale:));
        sq_swizzleSelector(class, @selector(descriptionWithLocale:indent:), @selector(sqjsonlog_descriptionWithLocale:indent:));
        sq_swizzleSelector(class, @selector(debugDescription), @selector(sqjsonlog_debugDescription));
    });
}

@end


#endif

三. 打印效果