[英]No matching function to call objc_getassociatedobject in ios
[英]How to store not id type variable use a objc_getAssociatedObject/objc_setAssociatedObject?
我使用了一個類別,並將一些變量存儲在UIView中。
但只存儲了id類型,所以我真的不想要id類型(int,float,double,char ......等等)
如何編寫代碼?
#import <UIKit/UIKit.h>
#import <objc/runtime.h>
@interface UIView (CountClip)
@property (nonatomic, copy) NSString *stringTag;
@property (nonatomic) float offsetY;
@end
#import "UIView+CountClip.h"
@implementation UIView (CountClip)
static NSString *kStringTagKey = @"StringTagKey";
- (NSString *)stringTag
{
return (NSString *)objc_getAssociatedObject(self, kStringTagKey);
}
- (void)setStringTag:(NSString *)stringTag
{
objc_setAssociatedObject(self, kStringTagKey, stringTag, OBJC_ASSOCIATION_COPY_NONATOMIC);
}
- (float)offsetY
{
// how to write a correct code?
return objc_getAssociatedObject(self, <#what is a code?#>);
}
- (void)setOffsetY:(float)offsetY
{
// how to write a correct code?
objc_setAssociatedObject(self, <#what is a code?#>,...);
}
@end
您需要將浮點數轉換為NSNumber實例,反之亦然:
static NSString *kOffsetYTagKey = @"OffsetYTagKey";
- (float)offsetY
{
// Retrieve NSNumber object associated with self and convert to float value
return [objc_getAssociatedObject(self, kOffsetYTagKey) floatValue];
}
- (void)setOffsetY:(float)offsetY
{
// Convert float value to NSNumber object and associate with self
objc_setAssociatedObject(self, kOffsetYTagKey, [NSNumber numberWithFloat:offsetY], OBJC_ASSOCIATION_RETAIN_NONATOMIC);
}
要存儲CGPoint
, CGRect
或CGSize
等變量, CGRect
查看NSValue
類並使用適當的方法:
NSValue *value;
value = [NSValue valueWithCGPoint:point];
value = [NSValue valueWithCGRect:rect];
value = [NSValue valueWithCGSize:size];
然后將其轉換回來:
NSValue *value = ...;
CGPoint point = value.CGPointValue;
CGRect rect = value.CGRectValue;
CGSize size = value.CGSizeValue;
供參考:
設置和獲取關聯對象的更快的方法可能是:
objc_setAssociatedObject(self, @selector(stringTag), stringTag, OBJC_ASSOCIATION_COPY_NONATOMIC);
objc_getAssociatedObject(self, @selector(stringTag));
這樣您就不必創建kStringTagKey
變量。
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