ios 6和7不会返回相同的结果 [英] ios 6 and 7 doesnt return same results

问题描述

似乎我们使用 getPropertyType（..）的应用程序在ios7下失败。无论出于何种原因， getPropertyType（..） on例如NSString属性返回 NSString $'\ x19 \ x03 \ x86 \ x13 作为类型，而不仅仅是NSString，而不是NSNumber，它返回 NSNumber \ xf0 \ x90 \ xae \ x04 \ xff \ xff \ xff\xff 。当我稍后检查特定类型时，所有这些都会导致一些棘手的问题。我已经改变了这个（遗产？）代码来使用 isKindOfClass ，但是我不理解我在这里发生了什么。

It seems that our apps which use getPropertyType(..) are failing under ios7. For whatever reason, getPropertyType(..) on for example a NSString property returns NSString$'\x19\x03\x86\x13 as the type, instead of just NSString, and also instead of NSNumber it returns NSNumber\xf0\x90\xae\x04\xff\xff\xff\xff. All of this is causing some tricky problems when i later on check against a specific type. I have changed this (legacy?) code to use isKindOfClass instead, but it bothers me that I don't understand whats going on here.

有问题的代码：

#import <objc/runtime.h>

static const char *getPropertyType(objc_property_t property) {
    const char *attributes = property_getAttributes(property);
    char buffer[1 + strlen(attributes)];
    strcpy(buffer, attributes);
    char *state = buffer, *attribute;
    while ((attribute = strsep(&state, ",")) != NULL) {
        if (attribute[0] == 'T') {
            return (const char *)[[NSData dataWithBytes:(attribute + 3) length:strlen(attribute) - 4] bytes];
        }
    }
    return "@";
}

到底发生了什么，为什么结果不同？

What on earth is going on, why are the results different??

推荐答案

getPropertyType返回的缓冲区未终止NULL。我认为这是唯一有用的运气。此外，返回新创建的NSData指向的数据并不能保证一旦该函数返回就会起作用。

The buffer returned by getPropertyType isn't NULL terminated. I think it's only dumb luck that it ever worked. Also, returning the data pointed to by a newly created NSData is not guaranteed to work once that function returns.

我将返回一个NSString。

I'd make this return an NSString.

NSString* getPropertyType(objc_property_t property) {
    const char *attributes = property_getAttributes(property);
    char buffer[1 + strlen(attributes)];
    strcpy(buffer, attributes);
    char *state = buffer, *attribute;
    while ((attribute = strsep(&state, ",")) != NULL) {
        if (attribute[0] == 'T') {
            return [[NSString alloc] initWithBytes:attribute + 3 length:strlen(attribute) - 4 encoding:NSASCIIStringEncoding];
        }
    }
    return @"@";
}

这假定为ARC。

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