[英]Pointer casting with ARC
ARC is giving me a hard time with following cast: ARC让我很难跟随演员:
NSDictionary *attributes;
SecItemCopyMatching((__bridge CFDictionaryRef)keychainItemQuery, (CFTypeRef *)&attributes);
Error: Cast of an indirect pointer to an Objective-C pointer to 'CFTypeRef ' (aka 'const void * ') is disallowed with ARC 错误:ARC不允许使用指向'CFTypeRef '(又名'const void * ')的Objective-C指针的间接指针
The problem is that attributes shouldn't be a dictionary, it should be a SecKeyRef or CFDataRef. 问题是属性不应该是字典,它应该是SecKeyRef或CFDataRef。 And then cast that back into NSData for the password data copied into it. 然后将其转换回NSData以获取复制到其中的密码数据。
Like so: 像这样:
CFDataRef attributes;
SecItemCopyMatching((__bridge CFDictionaryRef)keychainItemQuery, (CFTypeRef *)&attributes);
NSData *passDat = (__bridge_transfer NSData *)attributes;
As we were doing something similar things and using the example above, we were facing another problem: 当我们做类似的事情并使用上面的例子时,我们面临另一个问题:
CFDataRef resultRef;
OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)searchDictionary,
(CFTypeRef *)&resultRef);
NSData* result = (__bridge_transfer NSData*)resultRef;
This will result in an EXEC_BAD_ACCESS, because resultRef is not set to any adress and points somewhere to the memory. 这将导致EXEC_BAD_ACCESS,因为resultRef未设置为任何地址并指向内存的某处。
CFDataRef resultRef = nil;
This will fix the error. 这将解决错误。
Need to change attributes
to &attributes
需要将attributes
更改为&attributes
CFDataRef attributes;
SecItemCopyMatching((__bridge CFDictionaryRef) keychainItemQuery, ( CFTypeRef*) &attributes);
NSData* passDat=(__bridge_transfer NSData*) attributes;
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