Cannot use instance member within property initializer
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I have written a custom UIView and I found a strange problem. I think this is related to a very fundamental concept but I just do not understand it, sigh.....
class ArrowView: UIView {
override func draw(_ rect: CGRect) {
let arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x:bounds.size.width/2,y:bounds.size.height/3), endPoint: CGPoint(x:bounds.size.width/2, y:bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
let fillColor = UIColor(red: 0.00, green: 0.59, blue: 1.0, alpha: 1.0)
fillColor.setFill()
arrowPath.fill()
}
}
this code works fine but if I have grabbed this line out of the override draw function it does not compile. The error says I can not use the bounds property.
let arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x:bounds.size.width/2,y:bounds.size.height/3), endPoint: CGPoint(x:bounds.size.width/2, y:bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
Cannot use instance member 'bounds' within property initializer; property initializers run before 'self' is available
I don not understand why I cannot use this bounds out of the func draw
ios swift3
edited Jul 31 '17 at 21:03
Ryan Poolos
15.8k35590
asked Jul 31 '17 at 18:53
BillyBilly
1761116
add a comment |
I have written a custom UIView and I found a strange problem. I think this is related to a very fundamental concept but I just do not understand it, sigh.....
class ArrowView: UIView {
override func draw(_ rect: CGRect) {
let arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x:bounds.size.width/2,y:bounds.size.height/3), endPoint: CGPoint(x:bounds.size.width/2, y:bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
let fillColor = UIColor(red: 0.00, green: 0.59, blue: 1.0, alpha: 1.0)
fillColor.setFill()
arrowPath.fill()
}
}
this code works fine but if I have grabbed this line out of the override draw function it does not compile. The error says I can not use the bounds property.
let arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x:bounds.size.width/2,y:bounds.size.height/3), endPoint: CGPoint(x:bounds.size.width/2, y:bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
Cannot use instance member 'bounds' within property initializer; property initializers run before 'self' is available
I don not understand why I cannot use this bounds out of the func draw
ios swift3
edited Jul 31 '17 at 21:03
Ryan Poolos
15.8k35590
asked Jul 31 '17 at 18:53
BillyBilly
1761116
Possible duplicate of Error: Cannot use instance member within property initializer - Swift 3
– Filburt
Jul 31 '17 at 18:59
you can fix this issue by using computed property Example of Computed Property
– zombie
Jul 31 '17 at 20:19
add a comment |
I have written a custom UIView and I found a strange problem. I think this is related to a very fundamental concept but I just do not understand it, sigh.....
class ArrowView: UIView {
override func draw(_ rect: CGRect) {
let arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x:bounds.size.width/2,y:bounds.size.height/3), endPoint: CGPoint(x:bounds.size.width/2, y:bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
let fillColor = UIColor(red: 0.00, green: 0.59, blue: 1.0, alpha: 1.0)
fillColor.setFill()
arrowPath.fill()
}
}
this code works fine but if I have grabbed this line out of the override draw function it does not compile. The error says I can not use the bounds property.
let arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x:bounds.size.width/2,y:bounds.size.height/3), endPoint: CGPoint(x:bounds.size.width/2, y:bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
Cannot use instance member 'bounds' within property initializer; property initializers run before 'self' is available
I don not understand why I cannot use this bounds out of the func draw
ios swift3
edited Jul 31 '17 at 21:03
Ryan Poolos
15.8k35590
asked Jul 31 '17 at 18:53
BillyBilly
1761116
I have written a custom UIView and I found a strange problem. I think this is related to a very fundamental concept but I just do not understand it, sigh.....
class ArrowView: UIView {
override func draw(_ rect: CGRect) {
let arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x:bounds.size.width/2,y:bounds.size.height/3), endPoint: CGPoint(x:bounds.size.width/2, y:bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
let fillColor = UIColor(red: 0.00, green: 0.59, blue: 1.0, alpha: 1.0)
fillColor.setFill()
arrowPath.fill()
}
}
this code works fine but if I have grabbed this line out of the override draw function it does not compile. The error says I can not use the bounds property.
let arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x:bounds.size.width/2,y:bounds.size.height/3), endPoint: CGPoint(x:bounds.size.width/2, y:bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
Cannot use instance member 'bounds' within property initializer; property initializers run before 'self' is available
I don not understand why I cannot use this bounds out of the func draw
ios swift3
ios swift3
edited Jul 31 '17 at 21:03
Ryan Poolos
15.8k35590
asked Jul 31 '17 at 18:53
BillyBilly
1761116
edited Jul 31 '17 at 21:03
Ryan Poolos
15.8k35590
asked Jul 31 '17 at 18:53
BillyBilly
1761116
edited Jul 31 '17 at 21:03
Ryan Poolos
15.8k35590
edited Jul 31 '17 at 21:03
Ryan Poolos
15.8k35590
edited Jul 31 '17 at 21:03
Ryan Poolos
15.8k35590
15.8k35590
asked Jul 31 '17 at 18:53
BillyBilly
1761116
asked Jul 31 '17 at 18:53
BillyBilly
1761116
asked Jul 31 '17 at 18:53
BillyBilly
1761116
1761116
Possible duplicate of Error: Cannot use instance member within property initializer - Swift 3
– Filburt
Jul 31 '17 at 18:59
you can fix this issue by using computed property Example of Computed Property
– zombie
Jul 31 '17 at 20:19
add a comment |
Possible duplicate of Error: Cannot use instance member within property initializer - Swift 3
– Filburt
Jul 31 '17 at 18:59
you can fix this issue by using computed property Example of Computed Property
– zombie
Jul 31 '17 at 20:19
Possible duplicate of Error: Cannot use instance member within property initializer - Swift 3
– Filburt
Jul 31 '17 at 18:59
Possible duplicate of Error: Cannot use instance member within property initializer - Swift 3
– Filburt
Jul 31 '17 at 18:59
you can fix this issue by using computed property Example of Computed Property
– zombie
Jul 31 '17 at 20:19
you can fix this issue by using computed property Example of Computed Property
– zombie
Jul 31 '17 at 20:19
add a comment |
1 Answer
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So if we decode the error message you can figure out whats wrong. It says property initializers run before self is available so we need to adjust what we're doing since our property depends on bounds which belongs to self. Lets try a lazy variable. You can't use bounds in a let because it doesn't exist when that property is created because it belongs to self. So at init self isn't complete yet. But if you use a lazy var, then self and its property bounds will be ready by the time you need it.
lazy var arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x: self.bounds.size.width/2,y: self.bounds.size.height/3), endPoint: CGPoint(x: self.bounds.size.width/2, y: self.bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
answered Jul 31 '17 at 19:02
Ryan PoolosRyan Poolos
15.8k35590
add a comment |
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1 Answer
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1 Answer
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active
oldest
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oldest
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oldest
votes
So if we decode the error message you can figure out whats wrong. It says property initializers run before self is available so we need to adjust what we're doing since our property depends on bounds which belongs to self. Lets try a lazy variable. You can't use bounds in a let because it doesn't exist when that property is created because it belongs to self. So at init self isn't complete yet. But if you use a lazy var, then self and its property bounds will be ready by the time you need it.
lazy var arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x: self.bounds.size.width/2,y: self.bounds.size.height/3), endPoint: CGPoint(x: self.bounds.size.width/2, y: self.bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
answered Jul 31 '17 at 19:02
Ryan PoolosRyan Poolos
15.8k35590
add a comment |
So if we decode the error message you can figure out whats wrong. It says property initializers run before self is available so we need to adjust what we're doing since our property depends on bounds which belongs to self. Lets try a lazy variable. You can't use bounds in a let because it doesn't exist when that property is created because it belongs to self. So at init self isn't complete yet. But if you use a lazy var, then self and its property bounds will be ready by the time you need it.
lazy var arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x: self.bounds.size.width/2,y: self.bounds.size.height/3), endPoint: CGPoint(x: self.bounds.size.width/2, y: self.bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
answered Jul 31 '17 at 19:02
Ryan PoolosRyan Poolos
15.8k35590
add a comment |
So if we decode the error message you can figure out whats wrong. It says property initializers run before self is available so we need to adjust what we're doing since our property depends on bounds which belongs to self. Lets try a lazy variable. You can't use bounds in a let because it doesn't exist when that property is created because it belongs to self. So at init self isn't complete yet. But if you use a lazy var, then self and its property bounds will be ready by the time you need it.
lazy var arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x: self.bounds.size.width/2,y: self.bounds.size.height/3), endPoint: CGPoint(x: self.bounds.size.width/2, y: self.bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
answered Jul 31 '17 at 19:02
Ryan PoolosRyan Poolos
15.8k35590
So if we decode the error message you can figure out whats wrong. It says property initializers run before self is available so we need to adjust what we're doing since our property depends on bounds which belongs to self. Lets try a lazy variable. You can't use bounds in a let because it doesn't exist when that property is created because it belongs to self. So at init self isn't complete yet. But if you use a lazy var, then self and its property bounds will be ready by the time you need it.
lazy var arrowPath = UIBezierPath.bezierPathWithArrowFromPoint(startPoint: CGPoint(x: self.bounds.size.width/2,y: self.bounds.size.height/3), endPoint: CGPoint(x: self.bounds.size.width/2, y: self.bounds.size.height/3*2), tailWidth: 8, headWidth: 24, headLength: 18)
answered Jul 31 '17 at 19:02
Ryan PoolosRyan Poolos
15.8k35590
edited Jul 31 '17 at 21:05
answered Jul 31 '17 at 19:02
Ryan PoolosRyan Poolos
15.8k35590
answered Jul 31 '17 at 19:02
Ryan PoolosRyan Poolos
15.8k35590
answered Jul 31 '17 at 19:02
Ryan PoolosRyan Poolos
15.8k35590
15.8k35590
add a comment |
add a comment |
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Possible duplicate of Error: Cannot use instance member within property initializer - Swift 3
– Filburt
Jul 31 '17 at 18:59
you can fix this issue by using computed property Example of Computed Property
– zombie
Jul 31 '17 at 20:19