TextView自适改变高度

sizeWithFont:constrainedToSize:lineBreakMode:

 

 

Returns the size of the string if it were rendered with the specified constraints.

- (CGSize)sizeWithFont:(UIFont *)font constrainedToSize:(CGSize)size lineBreakMode:(UILineBreakMode)lineBreakMode

Parameters

font

The font to use for computing the string size.

size

The maximum acceptable size for the string. This value is used to calculate where line breaks and wrapping would occur.

lineBreakMode

The line break options for computing the size of the string. For a list of possible values, see “UILineBreakMode.”

Return Value

The width and height of the resulting string’s bounding box.

Discussion

You can use this method to obtain the layout metrics you need to draw a string in your user interface. This method does not actually draw the string or alter the receiver’s text in any way.

This method computes the metrics needed to draw the specified string. This method lays out the receiver’s text and attempts to make it fit the specified size using the specified font and line break options. During layout, the method may break the text onto multiple lines to make it fit better. If the receiver’s text does not completely fit in the specified size, it lays out as much of the text as possible and truncates it (for layout purposes only) according to the specified line break mode. It then returns the size of the resulting truncated string. If the height specified in the size parameter is less than a single line of text, this method may return a height value that is bigger than the one specified.

 

 

 

retun CGSize and get the value 

[curretSize hight];

 

CGRect * cg = [320,[currrent hight]];